In Spanish, subject pronouns are often omitted because the verb ending already shows who the subject is.
That’s why uso el ratón naturally means I use the mouse.
You could say yo uso el ratón, but that would usually add emphasis, contrast, or clarity.
Spanish often uses the present tense for general truths, habits, and repeated situations.
So:
means something like:
This is a normal way to express a real or habitual condition in Spanish.
The comma separates the if-clause from the main clause:
In Spanish, it is very common to put a comma when the si clause comes first.
If the order were reversed, the comma would usually disappear:
Both are correct.
Here el ratón means the mouse, referring to the computer mouse as a known, specific object in the situation.
Using el is natural because the speaker means the mouse they use, not just any random mouse.
Compare:
The accent mark shows where the stress goes: ra-TÓN.
Without the accent, Spanish pronunciation rules would suggest a different stress pattern, so the written accent is necessary.
This is just part of the correct spelling of the word:
It usually means any key in a general situation.
Even though una tecla literally means a key, in this kind of sentence it often has a general meaning:
So the speaker is not necessarily talking about one particular key on one particular keyboard; it can describe a general habit or rule.