لولا بساط التمرين لما استعمل صديقي شريط المقاومة.

Here لولا means if not for or were it not for.

So the sentence has this basic pattern:

• لولا + noun phrase = if it were not for ...
• لما + past verb = ... would not have ...

In this sentence, لولا introduces the thing that made the action possible: بساط التمرين.

Also note: لولا can have another use in Arabic, meaning something like why don’t / if only, but that is not what it means here. In this sentence, it is clearly the conditional if not for type.

Because in this pattern, لولا is commonly followed by a noun phrase, not a full verbal clause.

So:

• لولا بساط التمرين = if not for the exercise mat

Arabic often leaves the idea of existing / being there understood. So the sense is something like:

• If the exercise mat were not there...
• If it were not for the exercise mat...

That is normal and idiomatic Arabic.

No. This is a different function.

In this sentence, لما is part of the counterfactual result after لولا. It means something like:

• then ... would not have ...
• ... would not ...

So:

• لولا بساط التمرين لما استعمل صديقي شريط المقاومة = If it weren’t for the exercise mat, my friend would not have used the resistance band.

This is not the same as:

• لما = when
• لما = not yet

Arabic spelling is the same, but the meaning comes from the structure.

Because Arabic commonly uses the past tense in counterfactual constructions like this.

So after لولا, the result clause often uses:

• لما + past verb

Even though the verb is past in form, the whole structure expresses an unreal / hypothetical result, which English often translates with:

• would not use
• would not have used

depending on context.

So استعمل is grammatically past, but in this sentence it contributes to a counterfactual meaning, not just a simple past statement.

Because بساط التمرين is an iḍāfa construction (a possessive/genitive construction), literally:

• mat of exercise

In an iḍāfa:

• the first noun usually does not take ال
• the second noun can take ال
• the whole phrase can still be definite

So:

• بساط التمرين = the exercise mat
• literally: mat of the exercise

The same thing happens in:

• شريط المقاومة = the resistance band
• literally: band of resistance

This is another feature of iḍāfa.

In:

• بساط التمرين
• شريط المقاومة

the first noun is the thing being described, and the second noun defines it.

Structure:

• بساط = mat
• التمرين = the exercise

Together:

• بساط التمرين = the exercise mat

And:

• شريط = band/strip
• المقاومة = the resistance

Together:

• شريط المقاومة = the resistance band

The definiteness of the whole phrase comes from the second noun, so the first noun usually stays without ال.

صديقي is:

• صديق = friend
• ـي = my

So صديقي means my friend.

A few useful points:

• the suffix ـي is a possessive suffix
• once the noun has this suffix, you do not use ال
• the noun also no longer takes tanwīn

So:

• صديق = a friend
• الصديق = the friend
• صديقي = my friend

In the sentence, صديقي is the subject of استعمل.

Because verb–subject–object order is very common in Modern Standard Arabic.

So:

• استعمل صديقي شريط المقاومة = literally used my friend the resistance band

But natural English order is:

• my friend used the resistance band

Arabic could also say:

• صديقي استعمل شريط المقاومة

That is also possible, but it gives a slightly different flow or emphasis. The version with the verb first is very normal in MSA.

A fully vocalized version would be:

• لولا بساطُ التمرينِ لما استعملَ صديقي شريطَ المقاومةِ

Breakdown:

• بساطُ — nominative, because it is the noun after لولا in this construction
• التمرينِ — genitive, because it is the second term of the iḍāfa
• استعملَ — past tense, 3rd person masculine singular
• صديقي — the subject, meaning my friend
• شريطَ — accusative, because it is the direct object
• المقاومةِ — genitive, because it is the second term of the iḍāfa

In normal unvocalized writing, most of these endings are not shown.

Yes. Both استعمل and استخدم can mean to use.

So you could also say:

• لولا بساط التمرين لما استخدم صديقي شريط المقاومة

That would still be natural and correct.

Very roughly:

• استخدم is often very common in modern general usage
• استعمل is also correct and common, sometimes sounding a bit more formal depending on context

For a learner, it is good to recognize both.

Yes, it is understandable and natural.

Literally it means:

• band/strip of resistance

Depending on context, brand language, or region, you may also see other expressions, but شريط المقاومة works well in MSA and clearly communicates the meaning.

A learner should notice that Arabic often forms these kinds of technical or everyday compound nouns with iḍāfa, rather than using an adjective in the same way English does.