what is an accent..and how do I know my language accent that makes me speak differently from American? I speak Arabic And French (half Egyptian and half french and I moved to france recently, so mostly I was in Egypt). Does it really differ a lot from English? I read before that Arabic is a stress-timed language as English.

But what i don't understand is that everyone understands me clearly and i pronounce words correctly. is my problem with the language rhythm? i have been learning English since childhood, but i was taught by non-native English speakers.

How do I get rid of my accent if I have one?

Things I do: 1) Watching movies and shows without subtitles and mimic the actors. 2) listen to songs. 3) listen to radio shows. 4) listen to news. 5) watch youtube videos.
Note: I would like to have an American accent not just a clear foreign accent. Emotion: sad
Everybody has an accent, and even if you speak as a native they would have a regional accent. Don't worry about it.

If you aer being understood that is what language is all about. It may be the intonation and stressing as you mentioned if you are being told that you have a problem, but if natives ae just telling you have an accent then don't be overly concerned, it will also lessen in time.
If every native speaker has an accent, then we need to distinguish between native accents and non-native accents. If natives don't have an accent, then only non-natives do have an accent. Here, the question is not about the word or label--whether non-native accent or just accent: no matter what you call 'cancer', it remains a malignant disease. That is, we are referring to some phenomena in the world (what there is).

A) The vowel and consonant inventory
B) The allophony of the above (phonology, in other words)

C) Tone, tune, the contour of tunes
D) other paralanguage features, etc

What distinguishes natives from non-native speakers? A combination of all of the above. The material (descriptions) you find on these topics vary: number of materials on A > materials on B > materials on C > materials on D

Even though we all perceive differnce between natives from non-natives, we can't describe them. In order to describe these descriptions, we need theories (or systematic understanding) of both L1 and L2 in all aspects (A, B,C and D).