Can some one tell me what those 2 letter I circled in red mean?

Thank’s

 

They are the pin letter. A,b,c,d etc of the connector. Not sure why they pick random letters to display though. If you look at the connector to the left of the one you have highlighted, you will see it has the same letters, but in mirrored positions (as one is female and other is male) so when they mate A meets A, etc

 

I suppose it helps for when there's gaps between the pins. It DOES come in handy for the B1-01 (ECU) connectors

 

Ah ok, I thought it was another thing, because I am unable to find pin D where it is located in the diagram. Pin L ends in pin C of connector X-05 but I cannot understand where pin D ends.

thanks

 

The letters are reversed for the other connector. So A meets A, B meets B, etc. They are mirror images.
X-05 also is different if you have a manual or automatic. It's usually easier to just use the colors since the letters aren't listed completely. Using the manual, you need to use the first connector shown and start upper left to bottom right in order, and gets funky when the pins aren't right above each other. X-05 pin D is white/green for front side manual, red emission side manual, violet front side auto black emission side auto.
Again, just use the colors, it's rare to have more than one of the same in a connector and even then just tracing from the connector itself makes it easy.