אם יהיה חשמל במרפסת, אולי נוכל לשבת שם ולדבר על התחביבים שלנו.

Because יש is mainly used for there is / there are in the present tense.

Hebrew handles existence like this:

• יש חשמל = there is electricity
• היה חשמל = there was electricity
• יהיה חשמל = there will be electricity

So in future time, Hebrew normally uses a form of היה rather than יש.

That is a very common difference between English and Hebrew.

In Hebrew, when the condition is about the future, the verb after אם is often also in the future:

• אם יהיה זמן = if there is / if there will be time
• אם תבוא = if you come
• אם נוכל = if we can / if we will be able to

So אם יהיה חשמל is normal Hebrew, even though natural English usually avoids will in the if clause.

The verb agrees with חשמל, which is a masculine singular noun in Hebrew.

So:

• חשמל = masculine singular
• therefore: יהיה חשמל

If the noun were feminine singular, you would expect תהיה instead:

• תהיה תאורה = there will be lighting

Because Hebrew prepositions do not always match English ones one-to-one.

The prefix ב־ can mean several things depending on context, including:

• in
• at
• sometimes what English expresses as on

So במרפסת is the normal way to say on the balcony / in the balcony area.

This is just how Hebrew conceptualizes the location. You should learn במרפסת as the natural phrasing.

אולי means maybe / perhaps.

In this sentence, it softens the statement:

• אולי נוכל = maybe we’ll be able to

Its position is somewhat flexible. For example:

• אולי נוכל לשבת שם = maybe we can sit there
• נוכל אולי לשבת שם = we can maybe sit there

The version in your sentence sounds very natural.

In Hebrew, the verb itself usually tells you the subject, so the pronoun is often omitted.

נוכל already means we will be able / we can.

So Hebrew does not need אנחנו unless you want emphasis or contrast:

• נוכל = we will be able
• אנחנו נוכל = we will be able, with extra emphasis

This pronoun-dropping is very common in Hebrew.

Because the sentence is talking about a possible future situation.

• יכולים = can / are able, usually present
• נוכל = will be able / can, future

Since the meaning is something like if there is electricity, maybe we’ll be able to sit there, the future form נוכל fits best.

Also, נוכל is the 1st person plural future form of יכול.

Because after verbs like can / be able / want / need, Hebrew usually uses the infinitive.

So:

• נוכל לשבת = we’ll be able to sit
• רוצים לדבר or רוצים לדבר? Actually with רוצים, the infinitive is also used: רוצים לדבר = want to talk
• צריכים ללכת = need to go

Here:

• נוכל = we will be able
• לשבת = to sit

Together: נוכל לשבת = we’ll be able to sit

Because the second verb is also an infinitive, coordinated with the first one.

The structure is:

• לשבת = to sit
• ו־ + לדבר = and to talk

So ולדבר literally means and to talk.

Hebrew keeps the ל־ because the second verb is still dependent on נוכל:

• נוכל לשבת שם ולדבר = we’ll be able to sit there and talk

This is exactly parallel to English to sit there and talk, except Hebrew often keeps the infinitive marking clearly on both verbs.

שם means there.

It refers back to במרפסת and tells you where the sitting would happen:

• לשבת שם = to sit there

Its position is natural because it comes right after the verb it belongs to:

• לשבת שם = sit there

You could move it in some contexts, but this placement is the most straightforward and natural here.

Because לדבר על is the standard Hebrew pattern for to talk about something.

Examples:

• לדבר על סרטים = to talk about movies
• לדבר על העבודה = to talk about work
• לדבר על התחביבים שלנו = to talk about our hobbies

This is simply the usual verb-preposition combination you need to learn with דיבר.

Because התחביבים שלנו means our hobbies in a definite, specific sense.

Hebrew often uses:

• ה + noun + possessive word

So:

• הספר שלי = my book
• החברים שלנו = our friends
• התחביבים שלנו = our hobbies

Without ה־, the phrase can sound less definite, more like some hobbies of ours:

• תחביבים שלנו = hobbies of ours

In this sentence, the speaker means a specific set of hobbies, so התחביבים שלנו is the natural choice.