Po pierwsze pisze się advantages a nie adventages.
Pierwsze zdanie brzmi trochę dziwnie. Lepiej zacznij od tego "Being a teenager is a beautiful time, but it's a difficult(!) part of life for a lot of people. Adolescence has as many advantages as disadvantages.
Firstly, teenagers(!) don't have to work and earn money. Parents(!) take care of young people so their children(!) can think only about their education and(!) entertainment. It's very comfortable, because they can develope abilities and don't think about financial problems.
Secondly, it's the best time to fall in love. For example, a lot of people get married with girlfriends(!) or boyfriends "from their adolescence", (może lepiej ,who they met in adolescence.) Teenagers can spend all their free time close to their sweethearts. First love is(!) a beautiful and unforgettable experience for adolescents.
Also, (może moreover bo od also się raczej nie zaczyna zdania) young people make a lot of crazy and sometimes unpredictable things which aren't always good. Teenager's responsibility is not as big as adult's one. (!)A punishment is always lenient, because craze(!) is normal when people grow up.
On the other hand, adolescence has several disadvantages. For example, a (!)generation gap. Young people have absolutely other point of view than their parents or grandparents. (Ja bym to tak napisała) This is the reason of frequent arguments between members of family.
What's more,(!) adolescents can't do what they want. Their parents are responsible for them so they've got a big influence on their childrens' decisions.
In conclusion, being a teenager is the best period in every person's life. (Może coś takiego byłoby lepsze)It is normal that teenagers make many mistakes. That's why it is said that people learn from one's mistakes. I think that every person often mentions his/her adolescence. (bo piszesz person czyli 3.os l.poj.)
Ogólnie jest spoko. Tylko parę literówek się zdarzyło. Tam gdzie jest (!) znaczy że jakiś błąd był.