Hey guys new here and I was hoping someone would be able to offer me some help on why my chain keeps catching onto my 6th gear, when I'm in the 7th gear. I am very new with bike mechanics so please try and work with me on this
I'll post a picture of whats happening



Sorry about the quality, but as you can see, where I've circled is where the problem is occurring, and the arrow represents where the chain should be. It only gets caught on the gear for a second before latching back on to the last gear but still, my bike cannot be ridden while on the 7th gear because it happens every time you pedal. All other gears work fine.

Any observations, advice or help is much appreciated. Thank you for your time everyone.