The English modal "can" gets thrown around a lot where in other languages the main verb alone gets the meaning across.
"You can hear the birds" in English conveys two meanings;
You have the physical ability to hear birds
The birds are audible
Number 2 is what the Hebrew sentence for this exercise says. The modal verb "to be able" isn't necessary here.
In this unit we also introduce what we call the "impersonal plural". At times you may come across plural forms of verbs in Hebrew that are not connected to a personal pronoun. For example, a "normal" sentence with a plural form of a verb would be:<pre>
They eat apples. - .הם אוכלים תפוחים</pre>
But when you see a sentence like:
Does it mean "We eat", "They eat", or "You (all) eat"?
The answer is that it can be all of these and more! In fact, it is sometimes hard to translate this type of sentence into English without context. There are several options that can be considered:<pre>
One eats apples. (Can sound a bit old-fashioned nowadays.) You eat apples. (You as in "anybody" - can be confused for actual "you") We/They eat apples. (You have to know who is being spoken about, to know whether the speaker is including or excluding him/herself from the group) Apples are eaten. (At times using the passive can be the most elegant solution, but is not always an option)</pre>
Polyglots should be able to find parallels with the ways in which many other languages create impersonal expressions: French: On mange les pommes. German: Man isst Äpfel. Spanish: Se comen manzanas/Uno come manzanas. Dutch: Men eet appel.
At times it can also have a suggestive tone. For example, if someone says מדברים עברית, it can be equivalent to "one speaks Hebrew", but can also mean something like "you should be speaking Hebrew!".
At least in Spanish, Portuguese and Italian the construction using the reflexive pronoun (se, se and si respectively) although it is not a reflexive construction, is called the impersonal. It does not need a subject before the verb even though The English translation is usually “you, they or one” does something.
Even with taking into consideration the grammatical concept of impersonal plural, without the pronoun the sentence is ambiguous. In context, it can be an ellipsis, leaving out the obvious אנחנו or אתם or הם. It's not surprising that we might find such ellipses, after all Talmud Yerushalmi has all sorts of incomplete thoughts that apparently made sense once in context or if you become acquainted with talmudic modus operandi. The impersonal construction is in Mishnaic Hebrew (PerezFernandez, Introductory Grammar of Rabbinic Hebrew, p. 134). But even when the pronoun is not present, almost always the context allows you to figure out the implied subject. Sometimes that is the case because in an earlier clause there was "you" indicated somehow, or "one" fits well. I will add that impersonal speech is common in biblical Aramaic, for instance, but often the reader is given a clue based on a pronoun somewhere nearby (context). Aramaic characteristically uses the indefinite third person plural in place of the passive voice. The problem with the sentence in DL is that we have no context in which to know whether it is "one" or "you." Having written all that, it's helpful to know that modern Hebrew uses impersonal construction.