Is the career path interesting? I mean, is it possible to raise the salary over the years and, if yes, in what percentage?
If it's earnings that you are interested in, then no, the career path is likely to be a dead end with a low earnings cap. Most jobs of this sort are outsourced from wealthier counties, with the really interesting and well-paying jobs remaining in those countries. The primary reason they outsource the grunt work to countries like Poland is to save on wages, and you will quickly find that any decision they make regarding your eventual advancement will be primarily evaluated in terms of that.
Another thing that will greatly limit your ability to seriously advance is the relative lack of continuing education options. You will find little in this area until you master the local language. Courses offered in English at Polish universities are usually of abysmal quality, and the certificates or diplomas obtained will be of very little value, both inside Poland and abroad.
If your coming to Poland for a year or two of fun and adventure and to get a little useful experience to spice up your CV, then great. Go for it.
If your thinking of making a career in Poland as an accountant, think again. Your lifetime earnings potential in absolute Euros will be a fraction of what you can earn in a western country, and your absolute lifetime savings potential in absolute Euros will be an even smaller fraction, with greatly reduced chances for advancement. The difference in the cost of living will never offset the amount you lose.
As an accountant, you should be aware that the really interesting and rewarding jobs are for specialists and high level managers and consultants. You would be extremely foolish not to continually improve your qualifications, acquire new skills, and beef up the skills you already have. Your earnings are mostly limited by your knowledge of advanced applied mathematics and computer skills, especially programming and modeling. Management skills are also a big plus, but make sure to get them in an excellent management program at an excellent university. Language skills are also a plus, especially at the advanced near-native level rather than a superficial familiarity.
Getting a degree in financial engineering or actuarial mathematics would greatly increase your opportunities and earnings. High-level actuaries are in great demand everywhere, and will always be during your lifetime.
I'm guessing you're in your late twenties or early thirties. Focus on beefing up your education NOW
, because it's going to get harder as you get older. Take advantage of your youth while you still have it.