Learning A Second Language Can Make You Smarter and Help You Make Better Decisions?

I really hope this is true because most of the time, here in Japan, I feel so stupid. Like the other day my Japanese friends were having a very important conversation and then when they all looked at me to get my input I was like, "Uh... I like lamp?... I like... table?" What's even more pathetic is that I don't even actually know the Japanese words for lamp or table, so I didn't even say that.