If you can understand English, but you can't speak, this one's for you.
This is probably the most common problem that students learning a 2nd language face, and it has nothing to do with the language you're learning or your ability, the reason you can understand English, but the words just don't come out of your mouth is entirely due to the system you're using to learn.
I'll be honest, the way you learned English was probably not the best.
School curricula around the world, 10 to focus on vocabulary, grammar, reading, and writing.
These are for important skills to have in a 2nd language.
But what's missing, speaking, speaking, and verbal communication skills are not taught in many schools around the world.
I can speak to this firsthand.
I'm from Canada, and in Canada, we have 2 official languages, English and French.
There are French speaking parts of the country, and there are English speaking parts of the country.
I'm a native English speaker, and I was born in an English speaking part of the country.
