What does he mean when he says he wants a lowkey relationship?

I just recently told this guy all of my feelings for him and he said he feels the same. The only problem is he thinks if we become a couple we will break up and he'll lose me as a best friend. He said he likes me a lot but just wants to wait a little bit. Then he said he wanted a lowkey thing where we both like each other but we aren't titled as dating... What does this mean?
What does he mean when he says he wants a lowkey relationship?
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