The last day of weekdays [1]

It's Friday today, the day when we need to submit a work summary to our department manager.

After I sent the summary to the manager by email, I browsed English websites, but after some time, I just could not concentrate and could not absorb anything  [2]. Maybe it was becasue because I was tired, so I came to Italki for a break.

-----

[1] Your phrase is correct.  However, a native English speaker would use a different phrase: "The last day of the working week."

[2] You are correct, you can omit the second 'could not' and say, "I just could not concentrate and absorb anything."