Try the following code. I am parsing the entered String to make a Date

// To take the input
Scanner scanner = new Scanner(System.in);
System.out.println("Enter the Date ");

String date = scanner.next();

SimpleDateFormat dateFormat = new SimpleDateFormat("dd-MMM-yyyy");
Date date2=null;
try {
    //Parsing the String
    date2 = dateFormat.parse(date);
} catch (ParseException e) {
    // TODO Auto-generated catch block
    e.printStackTrace();
}
System.out.println(date2);

Other answers addressed how to use Scanner correctly. I'll address some other issues.

java.time

You are using troublesome old date-time classes, now legacy, supplanted by the java.time classes. Avoid the java.util.Date class like the Plague.

Also, you are inappropriately trying to represent a date-only value with a date+time class.

Instead, use java.time.LocalDate. The LocalDate class represents a date-only value without time-of-day and without time zone.

To parse the user's input, specify a formatting pattern to match exactly the expected input from your user.

DateTimeFormatter f = DateTimeFormatter.parse( "dd/mm/uuuu" );

Parse user input.

LocalDate ld = LocalDate.parse( input , f );

On your business class Guest, make the member variable of type LocalDate.

To persist the LocalDate, you can serialize to text in standard ISO 8601 format. Simply call toString.

String output = guest.getLocalDate().toString();

2017-01-23

About java.time

The java.time framework is built into Java 8 and later. These classes supplant the troublesome old legacy date-time classes such as java.util.Date, Calendar, & SimpleDateFormat.

The Joda-Time project, now in maintenance mode, advises migration to the java.time classes.

To learn more, see the Oracle Tutorial. And search Stack Overflow for many examples and explanations. Specification is JSR 310.

Where to obtain the java.time classes?

• Java SE 8 and SE 9 and later
  • Built-in.
  • Part of the standard Java API with a bundled implementation.
  • Java 9 adds some minor features and fixes.
• Java SE 6 and SE 7
  • Much of the java.time functionality is back-ported to Java 6 & 7 in ThreeTen-Backport.
• Android
  • The ThreeTenABP project adapts ThreeTen-Backport (mentioned above) for Android specifically.
  • See How to use ThreeTenABP….

The ThreeTen-Extra project extends java.time with additional classes. This project is a proving ground for possible future additions to java.time. You may find some useful classes here such as Interval, YearWeek, YearQuarter, and more.

You can do it like this

public static void main(String[] args) throws ParseException {

    Scanner userInput = new Scanner(System.in);

    System.out.println("Hello you, Lets get to know each other");

    String userName;

    System.out.println("What is your name ?");
    userName = userInput.nextLine();

    System.out.println(userName + " please enter you DoB (DD/MM/YYY)");

    String dateOB = userInput.next();
    Date date = new SimpleDateFormat("dd/MM/yyyy").parse(dateOB);
    System.out.println(dateOB);

    System.out.println("So your date of birth is " + dateOB);

    Calendar c = Calendar.getInstance();
    c.setTime(date);
    int day = c.get(Calendar.DAY_OF_YEAR);


    // IF day is from January 20 - to February 18 this means he or she is aquarius
    if (day >= 20 && day <= 49) {
        System.out.println("Aquarius");
    } else if (day >= 50 && day <= 79) {
        //If day if from February 19 to March 20 then pisces
        System.out.println("Pisces");
    }
    //write all zodiac signs ...

    userInput.close();
}

I recommend you switch from the outdated and error-prone java.util date-time API to the rich set of modern date-time API.

Define a formatter object:

DateTimeFormatter.ofPattern("dd/MM/yyyy")

…and use that same DateTimeFormatter object for both parsing and generating text.

import java.time.LocalDate;
import java.time.format.DateTimeFormatter;
import java.util.Scanner;

public class Main {
    public static void main(final String[] args) {
        Scanner scanner = new Scanner(System.in);
        System.out.print("Enter date in the format dd/MM/yyyy: ");
        String dateStr = scanner.nextLine();

        // Define a formatter
        DateTimeFormatter formatter = DateTimeFormatter.ofPattern("dd/MM/yyyy");

        // Parse the date string to LocalDate using the formatter
        LocalDate theDate = LocalDate.parse(dateStr, formatter);

        // Whenever you need to display it, display it using the same formatter
        String backToStr = formatter.format(theDate);
        System.out.println(backToStr);
    }
}

A sample run:

Enter date in the format dd/MM/yyyy: 21/07/2020
21/07/2020

A side note: I can see that you have created a new instance of Scanner for every input. You should create just one instance of Scanner and use the same instance for every input.