This is the IV of C major.
I’ve given the barre chord version and a simpler version. For the barre chord, hold your index finger across the first fret. Make sure you get a clean tone out of all six strings. This takes some practice, but it will eventually become second nature. What’s great about barre chords is that you can move them up and down the fretboard.
If this is too difficult for you at the moment, you can stick to the top four strings as shown in the second diagram. Xs mean that you should not sound those strings.
For the scale degrees of other keys than C major, look at this chart.