Exclusion is telling Avast not to scan what's excluded. I don't know what you are trying to find out?
Not speaking for the OP, but generally there are two (at
least) concerns that can arise with respect to excluded
folders.
(1) If a hacker or malware can identify which folders will
NOT be scanned by the security product in use then it is an
ideal place to copy malware.
(2) If a hacker or malware can not only read but also write
to the security product's exclusion list, then it can add
its own paths and filenames to that list.
Encryption of the exclusion list can prevent (1), as can
self-defense which prevents any and all accesses to the
product's data files including read access.
Self-defense mechanisms can also prevent (2).
Ideally all security products should implement such
protection schemes. I gather that the OP would like
to know if Avast prevents (1).