אני בכלל לא בטוח שיש לנו מספיק זמן לפני הפגישה.

Yes, Hebrew often can drop subject pronouns, because the verb form usually shows who is doing the action. But in this sentence, there is no finite verb in the first part in the same way English has I am. Hebrew often expresses to be in the present tense by simply putting the pronoun + adjective:

• אני בטוח = I am sure
• אני לא בטוח = I am not sure

So אני is needed here to make I explicit.

בכלל is a very common word with a few related uses. In this sentence, it strengthens the negation:

• אני לא בטוח = I’m not sure
• אני בכלל לא בטוח = I’m really not sure / I’m not sure at all

So here בכלל means something like:

• at all
• really
• in the first place, depending on context

In negative sentences, it often adds emphasis.

Because לא negates what follows. Here, בטוח is an adjective meaning sure/certain, so:

• בטוח = sure
• לא בטוח = not sure

That is the normal Hebrew way to say not sure.

Because בטוח is the masculine singular form. Hebrew adjectives agree with the speaker’s gender.

If a man is speaking:

• אני בכלל לא בטוח = I’m not at all sure

If a woman is speaking:

• אני בכלל לא בטוחה = I’m not at all sure

So the sentence as written sounds like it is spoken by a male speaker, unless it is just being cited in dictionary-style form.

שיש is basically ש־ + יש.

• יש = there is / there are
• ש־ = that

So:

• יש לנו מספיק זמן = We have enough time
• שיש לנו מספיק זמן = that we have enough time

In the full sentence:

• אני בכלל לא בטוח שיש לנו מספיק זמן
  = I’m not at all sure that we have enough time

In modern Hebrew, ש־ is very common as a connector meaning that.

Hebrew often expresses possession with יש ל־:

• יש לי = I have (literally, there is to me)
• יש לנו = we have (literally, there is to us)

So:

• יש לנו מספיק זמן literally means there is enough time for us
• but in natural English it is simply we have enough time

This is one of the most important basic Hebrew patterns.

מספיק means enough.

So:

• מספיק זמן = enough time

It comes before the noun here, unlike English, where enough usually comes after adjectives but before nouns:

• enough time
• מספיק זמן

You may also see מספיק used by itself in speech:

• מספיק! = Enough!

This is normal Hebrew word order. The clause after בטוח is:

• יש לנו מספיק זמן לפני הפגישה = we have enough time before the meeting

Broken down:

• יש לנו = we have
• מספיק זמן = enough time
• לפני הפגישה = before the meeting

Hebrew word order is often flexible, but this order is very natural and neutral.

It means before the meeting.

• לפני = before
• הפגישה = the meeting

So:

• לפני הפגישה = before the meeting

The preposition לפני can also mean in front of in other contexts, but here the time meaning before is clearly intended.

Because ה־ is the Hebrew definite article, equivalent to the.

• פגישה = meeting
• הפגישה = the meeting

So the sentence refers to a specific meeting, not just any meeting.

It sounds completely natural in both everyday speech and standard written Hebrew. A native speaker could easily say it in conversation.

A few notes:

• בכלל לא בטוח is very common in speech.
• The sentence is not especially formal.
• It sounds like normal modern Hebrew.

A slightly less emphatic version would be:

• אני לא בטוח שיש לנו מספיק זמן לפני הפגישה.
  = I’m not sure we have enough time before the meeting.

Adding בכלל makes it stronger.

If the speaker is female:

• אני בכלל לא בטוחה שיש לנו מספיק זמן לפני הפגישה.

If you want a less emphatic version:

• אני לא בטוח שיש לנו מספיק זמן לפני הפגישה.

If you want to sound more formal or slightly more literary, you might hear:

• אני לא בטוח שיש ברשותנו מספיק זמן לפני הפגישה.
  This is more formal than everyday speech.

But the original sentence is the most natural everyday version.