Because you need to improve your English if you are to be taken seriously by future employers.
For thr record, I went to the village primary school then the local comprehensive which I left at fifteen. The only qualifications I obtained were a CSE grade 1 in Physics and a CSE grade 1 in English Language. I did no higher or further education.
What I'm saying is that education does not begin and end in school. You should continue to learn for the rest of your life.