This is called the three four time signature. It tells you there are three counts in each bar. Three four time is also known as waltz time.
Before you sing this song, listen to the recording and clap along with the notes, counting 1 2 3, 1 2 3 as you go. Then sing the sol-fa syllables for the song and tap your foot on each beat of the bar as you sing. On the recording there are six drumbeats to introduce songs in ^ time (two bars).
A dot after a half note means that you hold the note for three beats.
This song contains a dotted half note in the final bar.
Don’t forget to practice singing each new song along with the recording, and also to practice each song with sol-fa syllables as well as the lyrics.