I have had guinea fowl for many years. I don't recommend taking in a single guinea. I have raised them with chickens and turkeys and will never raise them that way again.
Read the thread Raising Guinea Fowl 101 and pay particular attention to posts by @PeepsCA.
My recommendation is that you rehome it to someone who already has guineas.
Guineas are a flock bird that do best in large groups. I never recommend having fewer than 10 for proper flock dynamics.
If they haven't been imprinted by chickens, they can coexist. If they have been imprinted by...