The next song contains two curved lines called slurs. A slur indicates that the notes written above (or sometimes below) it should be played legato. Legato means to play the notes smoothly, so that they sound connected to each other. To play notes legato, keep your finger on the key until you have started to play the next key.
The letters above the staff are chord symbols. Do not play them now, but you can play along with them on the recording.