How to filter Unique values in a lookupvalue

Hi, Im trying to bring a category column from a diferent table without relationship, using a similar column in both tables to establish the relationship but one have more data than other and gives me this error where is expected single values in both:

I dont know how can I filter one of those columns so I have unique values in both.. i guess

ps: Im a newbie in PowerBI so apology in advance if this is basic stuff