Planers are not jointers, but
You probably have this in mind, a jointer:
If it's this one, it will have limitations because of the length of the beds/tables:
The confusion comes from someone in marketing who will forever remain nameless, called them jointer/planers. Eventually some people shortened it to "planers" and that's not what it is, even though it will "plane" off material from the bottom of the board. It's a jointer.
A planer, should really be called a "thickness planer" because that's what it does, makes a previously jointed board which has one flat side... an uniform thickness, removing material off the top of the board.
So, depending on what model you have in making the choice, the longer the tables, the better. A jointer has 2, a thickness planer has 1.
Post a photo if you can, usually older is "better", heavier more weight, cast iron etc. They are a little tricky to set up IF it's out of alignment, but we can help with that. New blades are also a bit tricky to set up/replace, but we can help with that also. :yes: