Today is rest day,but I have a meeting at three o'clock.
The weather is sunny ,but I can't go out to play with my friends.
A lots of people have a fever recently.
Today is rest day,but I have a meeting at three o'clock. The weather is sunny
,but I can't go out to play with my friends. A lots of people have a fever
recently.
Today is my day off.
A lot of people have fevers recently.
The first correction is not really wrong. But it makes you sound foreign.
Everything you wrote was well organized and totally understandable.