is there anyway to make my apple watch series 5 cel

A cellular Apple Watch has a Red Dot or Red Ring on the Digital Crown (that turnie, twistie thingie on the side).

You cannot add the cellular radio to a GPS only model.

What does "cel" mean?

Yes you have to buy an Apple watch cellular version,if you have the GPS only version then you need to have your phone with you,with the cellular version of the watch you can leave your phone at home.