Learn Portuguese (Portugal): É que, se eu comparecesse, perderia o meu trabalho. - The thing is, if I attended, I would lose my job.

É que is a very common conversational marker used to introduce an explanation or a justification for something previously said. Instead of translating it literally as "It is that," it is best understood as "The thing is..." or "It's just that...".

Why are we pairing the imperfect subjunctive (comparecesse) with the conditional (perderia)?

This is the standard grammatical formula for a hypothetical scenario. The condition part requires the imperfect subjunctive (se eu comparecesse) because it describes an imaginary or unlikely event. The result part requires the conditional tense (perderia) to state what would happen in that imagined scenario.

Could I just say se eu fosse instead of se eu comparecesse?

You could, but they carry slightly different nuances. While se eu fosse just means "if I went," comparecer means to "attend," "show up," or "make an appearance." It is often used for official commitments like a shift at work, a meeting, or an event.

Why is the "if" clause (se eu comparecesse) surrounded by commas here?

The discourse marker É que is directly introducing the main action (perderia o meu trabalho). Because the "if" clause (se eu comparecesse) interrupts that flow, it acts as an inserted condition and must be bracketed by commas in Portuguese.