Here's a brief explanation if you're new to reading chord diagrams:

Vertical Lines/Strings -  Thick/Left and Thin/Right

Horizontal Lines/Frets - 1, 2, 3, 4, & 5

Numbers/Fingers - 1/index, 2/middle, 3/ring, 4/pinkie

X - Don't play or mute with adjacent finger so there's no sound

O - Play the string open