This is the 12304th most frequent Polish word.
miło
"Miło" means "pleasantly" or "nicely" in English.
The word 'miło' here expresses a pleasant feeling or niceness associated with the action of seeing someone.
Miło cię widzieć.
Nice to see you.
Here, 'miło' is used to describe the pleasant quality of the shared experience of spending time together.
Było miło spędzić z tobą czas.
It was nice spending time with you.
In this sentence, 'miło' denotes a general pleasantness associated with people's smiles.