Fishing line recommendations

Hello.

I don't know much about fishing, my uncle wanted a reel who does a lot of fishing in the Caribbean. We ended up getting this one:

https://www.pennfishing.com/collections/pursuit/products/pursuit-iv-spinning-reel?variant=41966368751756

I've been trying to do research on what fishing line to get him with it but I am confused when it comes to the sizes (LB/MM). I am trying to get him a Monofilament and Braided fishing line.

Any advice, suggestions and recommendation would be greatly appreciated. Thank you!