"Yes, I am sorry!"
Przepraszam is a first person singular present tense verb. Przepraszać means to apologize.
Przepraszam, means phrases "I am sorry" and "Excuse me", it also means I apologize, or I am apologizing.
Ja przepraszam is I am sorry, or I apologize or I am apologizing, but with much more attention drawn to the I part of the sentence.
Is the 's' in 'fresh' pronounced or 'c' in 'cheese'? ;)
These are examples of digraph in English, which is an orthographical convention where two letters represent one sound and just as English, Polish has a few of them, namely: „ch”, „cz”, „dz”, „dź”, „dż”, „rz”, and „sz.”
„Rz” represents voiced retroflex fricative /ʐ/ and it's best approximation would be English 'zh' as in 'Zhivago'.
In Polish language there is only one present tense. This means that it often expresses the same things as English Present Simple and Present Continuous and even other tenses. So in this one and only present tense one never use constructions like „być” (to be) + verb and when it comes to modal verbs we use: „modał+ „infinitive”.
Also we normally drop prepositions as the ending of the verb often gives the same information. Leaving the preposition in Polish has different meaning, I.e underlining subject and showing contradictions.