Oops, be careful not to confuse these two words. Although both have a very similar sound and spelling, they have different meanings as well as pronunciation.
According to the Cambridge Dictionary:
1) SESSION /ˈseʃ. ə n/ - noun
a. [ C or U ] a formal meeting or series of meetings of an organization such as a parliament or a law court
The parliamentary session is due to end on May 27th.
b. [ C ] a period of time or meeting arranged for a particular activit
The 21-year-old runner twisted his ankle in a training session last Friday.
c. [ C or U ] any of the periods of time that a teaching year or day is divided into, or the teaching year itself
Access to these buildings is restricted when school is in session.
2) SECTION /ˈsek.ʃ ə n/ - noun
a. [ C ] one of the parts that something is divided into
the sports section of the newspaper
b. [ C or U ] specialized a cut made in part of the body in an operation
SECTION /ˈsek.ʃ ə n/ - verb
a. to officially force someone who has mental health problems to stay in a hospital and receive treatment because they might harm themselves or other people
He was sectioned under section 4 of the Mental Health Act.
P.S. [ C or U ] = countable or uncountable