Android Open Activity from FirstActivity

    Intent intent = new Intent(this, SecondActivity.class);
   
    intent.putExtra(EXTRA_MESSAGE, someMessage);

    startActivity(intent);

If you are trying inside onclick listener better to use Activity_Name.this insted of this

Intent intent = new Intent(FirstActivity.this, SecondActivity.class);

No data to send

startActivity(new Intent(FirstActivity.this, SecondActivity.class));

Receiving the Intent from Second Activity

Intent intent = getIntent();

String message = intent.getStringExtra(FirstActivity.EXTRA_MESSAGE);

ref: https://developer.android.com/training/basics/firstapp/starting-activity.html