Не торопись, а то успеешь.
When I started to tell you in some rush, I stopped and asked: "Успеваешь?"
As you could already understood there is no the same word in English. But for Russian it is quite common word.
I'll start with common use of this word.
English:
Will you on time for the train? or Do you have enough time?
literally we can translate
Ты будешь во время на поезд? Тебе достаточно времени?
First sentence has a right construction and you will be understood. But more common structure for it is:
Ты успеваешь на поезд?
We use this word when we have some limit (of time).
English. Before the meeting I had enough time to take a lunch.
Русский, дословно. Перед встречей у меня было достаточно времени для ланча (обеда).
Или. Перед встречей я успел поесть.
You can see that the second sentence is shorter but the meaning remained the same: I had a meeting, I was hungry, I had a time enough, I used the time to eat a meal.
If I'm waiting for you in a cinema and you're late, I'm calling you on the cell phone and asking: "Успеваешь?". I mean, will you come before a movie is started?
If I go to a cinema and you go to a railway station, your train departs at 17:15. I'm calling you at 17:20 and asking: "Успел?". Had you get on the train?
If I'm explaining you something that you didn't know before, I understand that some of terms you couldn't get (maybe you did, but I'm not sure), and I asking: "Успеваешь?" I mean: do you understand all that I'm talking.
If you've understood me right please try to translate the subject of this note.