This is the 17772nd most frequent Russian word.
улыбался
Smiled.
The verb 'улыбался' is used to express an ongoing action in the past, showing that the person was in the process of smiling.
Я посмотрел на него, и он улыбался.
I looked at him, and he was smiling.
Here, 'улыбался' indicates a repeated or habitual action in the past, as the act of smiling is accompanied by recollection.
Он улыбался, вспоминая что-то приятное.
He was smiling, remembering something pleasant.
Notice that 'улыбался' in this context places emphasis on the state of smiling that was occurring at the specific time of the arrival.