Language

This is a published rule, with a level. For a Dhaka student visa: IELTS 6 or above, or B2 Italian, issued within the last two years, unless your university has already verified your English on Universitaly (Dhaka checklist, MUR circular).

Three things that catch people out

1. A Medium of Instruction letter is not enough for the Dhaka visa. Your university may accept one for admission. The embassy's checklist asks for IELTS 6 or B2 Italian. Two different bodies making two different decisions, and clearing the first does not clear the second. See B6 and M7.
2. The two year window. A certificate issued more than two years before you apply does not count. If you tested early in a long cycle, check the date against your likely appointment rather than against today.
3. The Universitaly exemption is your university's call, not yours. It applies where the university has verified your English on Universitaly. Get written confirmation that yours has done it before you rely on it.

The level, in perspective

IELTS 6 is the visa floor. Your course may want more, often 6.5. Meeting the visa requirement is not the same as meeting your university's.

If you need to get there, the free IELTS course on this site is 195 lessons and costs nothing.