A banjo is naturally tuned in what is called “Open G Tuning.” The notes for each banjo string are:

1st String: D (the string furthest from your face as you look down while playing the banjo)

2nd String: B

3rd String: G

4th String: D

5th String: G (the shortest string that is closest to your face as you look down while playing the banjo)

If you are interesting in alternate tunings (which you shouldn’t worry about if you are a beginner) you can find some here: https://www.thebanjomountain.com/alternate-tunings/