canonical link is confusing

the smartcrawl says that my canonical is redundant (see here: in my theme options (divi) it is not enabled; should i enable it?

no matter how much i read about it, i don’t understand what i’m supposed to do with it. can you please clarify for me whatever i should do with this subject?

i want to add that all my broken links (404) are being re-directed (most of them) to the front page of my website ( i’m not sure whether i’m doing it right, therefore your help would be very much appreciated.

thank you!

p.s. support access is enabled. so please take a look. thanks again!