Fertile Window Confusion ... HELP!

So, I went to my Drs today and I spoke to him regarding TTC, yet again ....

He gave me this scenario regarding ovulation, this is what he said

'if you have a cycle which starts on the 1st Jan & end on 29th Jan (so a 28 day cycle), ovulation would occur 2 weeks prior to the end date, so the 14th Jan. You would start having sex 5 days before this & 5 days after'

This all makes complete sense however, the fertile window on my app shows a 10 day period before the ovulation.

My question is, do you only have sex within the fertile window OR do you also have sex on the days after your fertile window also?