Skip 3 Ch??

[K12butterfly]

Pattern says skip 3 ch, right after having done a 5-dc cluster. I’m still very new to crocheting so I am not sure exactly what that means

[bgs]

I am guessing from what little info that was given that you are working into your foundation chain and you most likely will  be making clusters all across.  Since you put 5 stitches into one chain the 5 stitches need a little space to "fan" out for the shell and this is done by not working into some of the chains.  Skip 3 chains means after completing your 5th dc in your cluster to count over and work your next stitch into the 4th chain (from the chain that the shell was made into). There will be 3 chains that nothing was worked into.

[K12butterfly]

Thank you for your reply. Yes I am working Into my foundation chain and what you explained makes a lot of sense so thank you. 

[Granny Square]

Is it a cluster? (meaning all the 5 stitches into 1 are connected at the top) or a shell? (5 unconnected stitches into 1 stitch, looking like a fan).

It doesn't matter as Bgs explained what to do either way, but just to describe the resulting appearance, in case you think you might have done something wrong: 

Because you are connecting the hook from the top of the cluster (or left stitch of a shell) to the chain, it's either going to make the cluster/shell lean to the left down to the skipped chains, or the sipped chains 'pull up' to the top of the cluster or shell.  It's not an uncommon thing in a lace pattern to use the foundation chain like this; foundation chains are not always just a straight line.