Console 창에서는 'ArgumentNullException: Value cannot be null. Parameter name: source UnityEngine.AudioSource.Play () (at <8e2857b79be4468ca1c28dda75978191>:0) BirdJump.Update () (at Assets/BirdJump.cs:23)' 라고 뜨네요.
This is the 2D forum and your post has nothing to do with 2D features or issues. You don't actually ask a question although we can guess you're following a tutorial(?) and have got it wrong because you've got an ArgumentNullException. The error clearly tells you the problem though; you're passing a NULL on Line 23 to the AudioSource.Play call. It even tells you the specific argument that is NULL. Probably because you have a field of type "AudioSource" but it's not been assigned to anything yet. Your post belongs on the scripting forum here so I'll move it.