Dialects are how people speak in different ways in a particular area or among specific people.
Have you noticed that people have different ways of pronouncing certain words and phrases and at times they even speak differently so you figure it out that they don’t speak the same way like how others speak?
There are a number of countries that are English-speaking and some of them are America, England, Australia, and even Ireland that has native-English speakers. There are even more dialects in each of these countries. When you are learning the English language, the means and resources that you will choose will play a big role. It will be different if you learn dialects and English from TV shows and it will be different if you learn the same from any textbook or any website.
Your decision to choose will make a big difference and remember that dialects have different spellings, common phrases and there are even differences in speech that include pronunciations and accents.
The main question is that why are you learning English?
Is it because you want to be a professional English speaker, or you want to move to an English-speaking country for your further studies or work or do you just want to learn English so that you can communicate with people?
If you are learning English just to be on the social media handles, then you may choose and learn and dialect you wish to learn. It will be much easier to pick a dialect if you know a reason as to why are you learning English.
Remember that if you are not known to any dialect, it will be difficult for you to understand them. The best way to learn and practice is by talking to people every day.
Don’t forget to practice and stay consistent with what you are learning!