We seemed t have 'acquired' a feral cat and is now living under a newly built shed. It used to eat the food that was left out, now, it grabs it and takes it back underneath, we're not sure if it is male or female as I don't know anything about cats.
I do know it lifts it's tail and sprays a lot. Please can you assist? Thank you.

Urine Marking in Cats | ASPCA

You probably have an un-neutered male.

I am not in favor of feeding feral cats, because they multiply like rabbits and cause huge problems, including increased suffering for feral cats as a whole. But many don't agree with me.

Call a local animal shelter or animal control. They will trap it and remove it.