To "provide (someone) with assistance" just means to help them. So the following phrases have nearly the same meaning:

Any assistance you can provide would be greatly appreciated.

Any help you can give would be greatly appreciated.

But "assistance" is a more formal word than "help". In case you don't know or you want to learn more about the differences between formal and informal writing, read more at AcademicHelp.net.

"Provide" is also formal. It means to give something or to make something available for people to use:

These results provide support for the theory that humankind evolved speech later than scientists had previously thought.

"Provide ___" is really common in writing. Here are some of the most common things that people "provide":

provide information

provide opportunities

provide assistance

provide health care

provide insurance

provide training