Create an Apex class with a method that returns an array (or list) of strings.

StringArrayTest.apxc

public class StringArrayTest {
    public static List<String> generateStringArray(Integer length) {
        List<String> retArray = new List<String>();
        for(Integer cnt = 0; cnt < length; cnt++){
            List<String> params = new List<String>{ String.valueOf(cnt) };
            String elemStr = String.format('Test {0}', params);
            retArray.add(elemStr);
            System.debug(elemStr);
        }
        return retArray;
    }
}

public class StringArrayTest {
public static List generateStringArray (Integer length) {
List strList = new List();
for(Integer i=0; i<length; i++) {
String text ='Test ' + i;
strList.add(text);
}
System.debug(strList);
return strList;
}
}