Why it can't be "a dry bread"?
In English, "a" goes before only things that can be counted. Bread cannot be counted in English, so "a" cannot go with it.
Why you not counted, it is..
A loaf of bread is countable as opposed to bread itself.
Does this only mean dry, rather than wet, or can it also mean that's she's eating stale bread?
It could mean stale.
Can this also mean that "she eats dry bread" in general, as opposed to her currently eating it
Yes, no distinciton in Hebrew.
When do you know that ל is a instead of the? Because I put "the dry bread" and it was counted as wrong.
"The bread" would be: הלחם
The prefixe "ל" means to/for. "לך ל-חנות: Go to the store"
Get some butter, woman!
Why is "she eats matzah" wrong? XD
Well, מַצָּה is a special kind of bread, but לֶ֫חֶם יָבֵשׁ can be ordinary bread, which has become stale.
Would "dry bread" be considered matzah? Or something different.
Not matzah. Just bread that became dry due to being not fresh.
I put עבש and it was marked correct??
Well, as לֶ֫הֶם עָבֵשׁ is moldy bread, I would prefer לֶ֫חֶם יָבֵשׁ dry bread if having a choice.
If that's what she likes why not?
Sure, but in a translation exercise she does not have that choice :-)