This is simple code to do it, I avoided all checks but this is the main idea.

 public String parse(String jsonLine) {
    JsonElement jelement = JsonParser.parseString(jsonLine);
    JsonObject  jobject = jelement.getAsJsonObject();
    jobject = jobject.getAsJsonObject("data");
    JsonArray jarray = jobject.getAsJsonArray("translations");
    jobject = jarray.get(0).getAsJsonObject();
    String result = jobject.get("translatedText").getAsString();
    return result;
}

To make the use more generic - you will find that Gson's javadocs are pretty clear and helpful.

Based on the javadoc for Gson 2.8.6

No need to instantiate this class, use the static methods instead.

and following are the alternatives to be used.

// jsonString is of type java.lang.String
JsonObject jsonObject = JsonParser.parseString​(jsonString).getAsJsonObject();

// reader is of type java.io.Reader
JsonObject jsonObject = JsonParser.parseReader​(reader).getAsJsonObject();

// jsonReader is of type com.google.gson.stream.JsonReader
JsonObject jsonObject = JsonParser.parseReader​(jsonReader).getAsJsonObject();

Example

import static org.junit.Assert.assertTrue;

import com.google.gson.JsonObject;
import com.google.gson.JsonParser;

public class Test {

    public static void main(String[] args) {
        String jsonString = "{ \"name\":\"John\"}";

        JsonObject jsonObjectAlt = JsonParser.parseString(jsonString).getAsJsonObject();
        // Shows deprecated warning for new JsonParser() and parse(jsonString)
        JsonObject jsonObject = new JsonParser().parse(jsonString).getAsJsonObject();

        assertTrue(jsonObjectAlt.equals(jsonObject));

    }
}