太阳 (tàiyáng) means 'the sun.' It is the standard word for the sun in modern Chinese. It is used in everyday expressions like 太阳天 (sunny day) and 晒太阳 (to sunbathe).
今天太阳很大,出门记得戴帽子。
Jīntiān tàiyáng hěn dà, chūmén jìde dài màozi.
The sun is very strong today; remember to wear a hat when going out.
早上的太阳刚升起来,特别漂亮。
Zǎoshang de tàiyáng gāng shēng qǐlái, tèbié piàoliang.
The morning sun has just risen and is especially beautiful.
老人们喜欢在公园里晒太阳。
Lǎorénmen xǐhuān zài gōngyuán lǐ shài tàiyáng.
Elderly people like to bask in the sun in the park.