There are 3 difficulties that my mom has to face in life, they are struggling to understand all the things that “kids are up to these days”, keeping you away from old family secrets and feuds and turning a blind eye when you messed up or did something wrong. First of all, being your go-to confidant is a task your mom gladly accepts, but it also means that she has to work hard if she wants to keep up with the younger generations. When she talks to you she needs some sort of context and at least a rudimentary understanding of youth culture if she wants to relate, and it can be confusing and tiring for her at times. Being the cool and understanding mom requires patience and quite a bit of research on the side. Second, if you have had a relatively fun and relaxed childhood, all things considered, then you probably owe your mom a huge gift. All families will have some traction, all kinds of small feuds and issues, and perhaps a few skeletons in the closet. It’s up to moms to act as a buffer between their children and the turbulent relations within the family, always keeping their chin up and a smile on their face. Last but not least, while most of us like to think that we were pretty good as children, the truth is that kids can be quite the handful at times. It takes a lot of time to develop a strong sense of right and wrong, and learn how to behave, and our moms tend to be incredibly patient throughout our different developmental stages. We would break things and lie about it, even though it was obvious we did it, or we’d make the very mistakes our mother told us how to avoid; yet mom would sometimes skip the stern talk and let one slide if she felt that we felt very bad about it.

The passage above is just a correction of grammatical points. You have a really wide range of vocabularies and use them very well. I see lots of linking words as well as advanced-level words. But if I were you, I would write it like this:

In everyone's soul, there always is an image of a person whom they love most. And in mine, that image is of my mother's. This year, she's nearly 40 years old. My mother is tall, pretty with a round face and brown hair. To my ways of thinking, she is the most beautiful woman in the world. My mother cooks really well and always takes responsibilities for her work. Especially, she plays badminton very well, which comes as a surprise to many people, even me. I love my mother as she can sacrifice anything for me. She always shares with me the problems in life, at school and encourages me whenever I have bad marks or any sorrow. And when I achieve anything in my studying, she always prepares a present for me. There is unforgettable moment between me and my mother. One night, I had an illness and felt too sick to stand. My mother spent a sleepless night to take care of me. And when I was better, I asked my mother if she was tired. She said "No". At that time, I realised, mothers will never feel tired when taking care of their children. I love her so much and I'll try my best to make her happy and always keep the smiles on her face!!!

Because at some points, you use high-level words, and at others, you use simple words. If the level is equal in the whole passage, it's much better and shows your level. This will make your writing interesting in other examiners' eyes.