Old thread I know, but I've been involved with bearings in an earlier life so ...
6205 is the bearing description, its a single row deep groove ball bearing, 25 mm ID X 52 mm OD x 15 mm W.
The suffixes refer to two rubber seals, 2RS is a contact seal which rubs on the flat of the inner race just like an oil seal rubs on a shaft. UU is one manufacturer's code for non-contact rubber seal (VV is used by NSK I think, there's also 2RU used by other manufacturer/s). These usually have a split lip, and the two lips run in grooves in the inner race and don't touch the inner race at all - it's a labyrinth seal like an upside down V running in a W. The difference is pretty esoteric, the 2RS seals give fractionally better water protection but create a small amount of friction, the UU seals can allow slight passage of water into the bearing but don't create drag.
Personally, I'd use the 6205-2RS. Just look for an engineering supply company which is a distributor for SKF, FAG, NSK, NTN, or any other major bearing company, they'll all recognise 6205-2RS and will have them in stock.