This is the 258th most frequent Vietnamese word.
chăm
"Diligent" or "hardworking."
Here, 'chăm chỉ' refers to being hardworking or diligent in an activity.
Bé rất chăm chỉ học bài mỗi ngày.
The child is very diligent in studying every day.
In this sentence, 'chăm sóc' means to take care of or to look after someone.
Chị ấy chăm sóc mẹ rất chu đáo.
She takes care of her mother very thoughtfully.
'Chăm' in this context means to look after or cultivate plants.