This is the 5186th most frequent Korean word.
늘었는데
"늘었는데" means "improved, increased, or grew, but/and..." depending on context.
Here, '늘었는데' indicates an improvement or increase in Korean skills, presenting it as a context for the happiness expressed in the second clause.
한국어 실력이 많이 늘었는데, 시험을 잘 보게 돼서 기뻐요.
My Korean skills have improved a lot, so I'm happy that I was able to do well on the test.
In this sentence, '늘었는데' refers to an increase in the number of friends, leading to a situation of not feeling lonely.
친구가 늘었는데, 이제 외롭지 않아요.
I've made more friends, so I'm no longer lonely.
Here, '늘었는데' describes the increase in the number of stores, introducing a plan to visit as a consequence.