bardzo spokojny in English:

Today's serene sky makes me very optimistic.

Her face was serene.

"he remained serene in the midst of turbulence"; "a serene expression

He apologizes to Mike, who is sitting there like a serene Buddha.

I think that such a serene person cannot be dangerous.

It was important to her that her environment be calm and serene, free from drama and chaos.

Your daughter is so serene!

She has a lovely serene face.

I feel mermaid - beautiful and serene

The autumn sky is clear and serene.

The view of Mars through earthly telescopes suggested that all was serene.