It appears to be gray, but, it doesnt look like caulk to me, it looks like grout, and it should never have been grouted, it should have been caulked. All that has to be picked out of there, before you can redo it. You want to use a caulk with silicone in it. If any part of what you need to be caulked is also painted, you need a caulk with silicone that can be painted. It will say paintable on the tube. Buy the best quality caulk, you can find. It will be less work in the long run. Please post pictures here in the comments, and take more of them, so we can see the entire area.

It looks like someone tried to caulk over a grouted corner.

You should scrape out what you can of the grout in there - get a tool with a sharp point and scrape it out (it won't be easy) . Rub your fingers down the tiles to remove the light strip of caulk that IS on the tile - like dried glue.

Then get a good silicone based caulk in a fairly light gray.

When clean and dry, tape down each side of the corner about 1/8" from the corner. Press and seal the edge of the tape (blue painters).

Run your caulk bead down between the tape - using a pretty small tip.

I use a popsicle stick to then "tool" the caulk (you may remove quite a bit if you made the hole too big in the tube) . if you do it right, you can have one smooth motion - keeping the stick at the same angle. The key to a clean job is to match the curvature of the popsicle stick as closely as possible to where the tape edge is - that will give you a straight, smooth, perfect line.

Remove tape and let harden.

So helpful! thank you! Any brand you would recommend?

I found this tool handy for caulking... any home center should have one and they're cheap

https://www.homedepot.com/p/HDX-2-Piece-Caulk-Tool-CTK-HDX/206509482

Any name brand silicone caulk will do - and get paintable if you want - but you don't need it in a shower corner. ;-)

If you tape and use the dry tooling - you can be a pro with practice. ;-) . That method provides a much crisper caulk line than the "wet your finger and smooth" approach.