This is well written and I can see you have good knowledge of sophisticated grammatical structures! Just a few small corrections. I hope this is helpful and let me know if you have any other questions. Good luck!

In the year 2020, I will be graduated in my undergraduate degree... 

Dont say "I will be graduated" but "I will have graduated" You can say "I will have graduated from university" OR "I will have completed my degree" (We don't really say "graduated in my degree") 

and I already have new plans being planned for the year 2021

A more natural way of saying this would be "I am already making new plans for the year 2021". We typically use the verb 'make' when talking about plans. 

You could also say "I have begun making plans for 2021". 

For these plans to be successful, I especially need my English to be advanced.

In 2017 I started a course to study English and I'm about to finish, but my listening and speaking are still very bad, as well as having great difficulty in writing long texts and interpreting them.

A more natural way of saying this: "In 2017 I started an English course..."  I would also split the sentence with 'and' to make it tidier "but my listening and speaking are very bad and I also have great difficulty writing long texts and interpreting them."

....
Hi, could you please fix it for me?
Thank you!

My Plans

Good luck with your English! If you need any help with listening and speaking I can help you :-) Andrea