It is possible to sing and play a guitar at the same time but this can be a little difficult for a beginner. A good sense of rhythm and the ability to synthesize two different actions is needed to pull this off.
This act can be mastered just as you learned how to play the guitar. As you continue to practice both activities simultaneously, you will develop muscle memory for doing both activities at the same time.
You need to learn the song first, and then learn how to play rhythm cords. With practice and dedication you will be able to carry out the two activities at once.
Singing and playing guitar together can be tricky for a beginner, but it is entirely possible. It takes practice and dedication as you will have to grasp the basics of the guitar. You will need to learn to play rhythm chords and be able to hold a rhythm for vocals. You will first need to learn the song you are going to sing.
Next, you need to learn to play with rhythm while counting aloud, then start adding words. Next, play the song, but try not to think about the chords and practice until it becomes like second nature. Doing all of this requires a sense of timing, rhythm, and ability to combine two actions at once.