Rightly or wrongly, the way that you speak is one of the first things that people notice about you. Do you know that people will judge your background, education and social standing just by the way you speak?
Even if you can already communicate well in English if you do not speak clearly enough, people around you will not understand you and they might not even want to talk to you. Why? Because it is just too tiring to try to understand you!
Listening and understanding go hand in hand. If you do not know how different words are pronounced you will not improve your understanding of English.
1. Please do not confuse your pronunciation with your accent (we do not all have to talk like the Queen of England, really!) As long as your pronunciation is understandable and pleasant to hear by others that is just fine.
2. However, if people tell you that they struggle to understand you then you may need to try and reduce your accent but unless you are an actor and you need to play different roles, just keep in your accent (and do not copy anyone else's too please, that is just fake).
3. Successfully speaking in English is more than just knowing how to pronounce words correctly, there are other sub-skills that you have to learn.
4. Two additional sub-skills that you must learn are: 'enunciation' = the act of speaking clearly and concisely, making each word sound as clear as possible AND 'elocution' = meaning you know how to put the right emphasis and nuance into what you are saying.