The Portuguese word for sun is
sol

Gender

The gender of sol is masculine. E.g. o sol.

The plural of sol is sóis.

sun
1. Substantivo. Sol

Sol
1. Proper noun. (astronomy) the Sun
2. n-m. sun (a star, especially when seen as the centre of any single solar system)
3. n-m. sunshine (a location on which the sun's rays fall)
4. n-m. weather (the state of the atmosphere at a specific time and place)
O sol frio de inverno. - Winter's cold weather.
5. n-m. sol (a musical note)
6. n-m. (chemistry, physics) sol (a colloid suspension of a solid in a liquid)