Tails and the meaning of the word.
The Polish language is rich and various. One of the most important differences, between Polish and, for example, English signs is using 'tails' (in Polish 'ogonki'). In Polish a few letters, like a,e,o,n,l are in two forms: basic, and modified. 'Tails' is the modification we make to change the spelling of a letter, to make it softer, or more fluent. Letter 'l' with 'tail' will look like this: 'ł'. Spelling of 'l' is like 'l' in word 'swallow'. The 'ł' is rather like 'w' in the word 'cow'. Difference is huge.
That is why it is so important to use them correctly by pressing the right ALT on the keyboard. Using o tail can completely change the meaning of the word.