Hi Ashraful,
Both of these would be understood by a native speaker, but it's not something we would say. "To the level" isn't a standard English expression, but you might see variations of this where "level" is used to mean "standard".
In this dictionary entry (
https://www.merriam-webster.com/dictionary/level), this is the 5th meaning of the word:
* "a position in a scale or rank (as of achievement, significance, or value)"
-- "funded at the national level"
-- "the job appeals to me on many levels"
Your first sentence might be: "It's very important to learn the language to a level where you can be understood." In other words, "Your standard/quality needs to be good enough that people can understand you."
"He speaks English to an advanced level." / "His English is of a very high quality."
For your second sentence, you would probably just use "until": "I have to work out at least until I look good."
I hope that helps!