1. I have two health educations on Monday.

2. I have two healths on Monday.

[As a subject taught by a school nurse, which one is right, 'health education' or 'helth'? Which one is correct in the two sentences above?]

We would say "two health classes".

The correct phrase to use in this context is "health education." So, the first sentence would be correct as "I have two health educations on Monday." The second sentence, "I have two healths on Monday," would not be grammatically correct.