What you mother toungue is matters very much as it influences the kind of mistakes you will tend to make in foreign languages.

Sounds, words and grammar structures that do not exist in your mother toungue are often very hard to grasp in a new foreign language.

So if you are not sure you may try as good as you can - or even guess.

Languages always allow for some variation around a certain sound as long as it causes no confusion. It is only important to make a distinction if it carries a meaning. And as different people vary in pronounciation the "space" around a sound tends to fill with slight variations which still are understood correctly. This will also affect the hearing process so the brain will often lose the ability to make the distinction.

The classical example is of course Japanese and Chinese speakers who are ridiculed for not being able to use R or L in the right spot (actually spills over to spelling as well). In this case i know only about Japanese that there is one sound in the language somewhere between R and L. So the R/L distiction carries no meaning.

Arabic has only three vowels so the "space" occupied by each vowel is much larger than for example in Swedish where there a 17 different vowel phonems (sounds). So for a native Arab speaker using the right vowel is a great challenge.