Huwag mong kalimutan ang dyaket mo kapag sasakay tayo ng tren.

Huwag is used for negative commands or prohibitions, so it means don’t.

• Huwag mong kalimutan... = Don’t forget...
• Hindi is used to negate statements, not commands.

So:

• Hindi ko alam = I don’t know
• Huwag mong gawin iyan = Don’t do that

Mong is basically mo plus the linker -ng.

In Huwag mong kalimutan, the -ng helps connect mo smoothly to the next word, kalimutan. This is a very common pattern, and learners often just memorize it as:

• huwag mong + verb
• sabihin mong + ...
• isipin mong + ...

So mong is not a different pronoun from mo in meaning. It is still you/your, just in a linked form.

The root is limot, which relates to forgetting.

Kalimutan is the verb form used when the sentence focuses on the thing being forgotten. In this sentence, the specific thing is ang dyaket mo.

So:

• Huwag mong kalimutan ang dyaket mo = Don’t forget your jacket

This is a very natural pattern in Filipino:

• Huwag mong kalimutan ang susi = Don’t forget the key
• Huwag mong kalimutan ang pangalan niya = Don’t forget his/her name

Because ang does not always mean the English subject.

In Filipino, ang marks the topic/focus of the clause. With kalimutan, the thing affected by the action is the focused element, so it gets ang.

That is why:

• Huwag mong kalimutan ang dyaket mo

Even though in English your jacket looks like the object, in Filipino it is the ang-marked element because of the verb form used.

They do two different jobs.

• The first mo in mong refers to you, the person being told not to forget.
• The second mo in dyaket mo means your, showing possession.

So the sentence is literally structured something like:

• Don’t you forget your jacket...

It may look repetitive to an English speaker, but it is perfectly normal in Filipino.

Filipino pronouns come in different sets, and the verb pattern affects which set is used.

Here:

• mo is from the ng-set/genitive set
• tayo is from the ang-set/nominative set

Why the difference?

• In Huwag mong kalimutan, the verb form kalimutan takes the doer in the ng-set, so you get mo.
• In sasakay tayo, the verb form sasakay takes the doer in the ang-set, so you get tayo.

This is one of the big differences between Filipino and English: pronoun form changes depending on the verb pattern.

Kapag means when or whenever, especially for future or expected situations.

In this sentence:

• kapag sasakay tayo ng tren = when we ride / when we are going to ride the train

It is commonly used for events that have not happened yet.

Also:

• pag is a shorter, more casual form of kapag
• kung usually means if, not when

So here kapag is the natural choice.

Sasakay is the future or contemplated aspect of sumakay, which means to ride, to board, or to get on.

For many -um- verbs, the future form is made by:

• repeating the first syllable of the root
• leaving out -um-

So:

• sumakay → sasakay

This can mean:

• will ride
• are going to ride
• will board

depending on context.

Because tayo includes the person being spoken to.

Filipino makes an important distinction:

• tayo = we, including you
• kami = we, excluding you

Since the speaker is telling the listener Don’t forget your jacket when we ride the train, the listener is part of that we, so tayo is correct.

With sumakay / sasakay, both ng and sa can appear, but the nuance is a little different.

• sasakay ng tren often means ride/take a train
• sasakay sa tren often emphasizes getting on the train

So in this sentence, ng tren presents train as the vehicle being taken.

A simple way to remember it:

• ng = the vehicle being used
• sa = the vehicle/place being boarded or entered

In real usage, both can be heard, but ng tren is very natural here.

Yes. Dyaket is a Filipino spelling of English jacket.

Many Filipino words are borrowed from English and then spelled in a way that matches Filipino pronunciation and spelling patterns.

So:

• dyaket = jacket

You may also hear some speakers use the more English-like pronunciation, but dyaket is a normal Filipino written form.

Yes, but the given order is the most natural and straightforward.

The normal Filipino pattern is often:

• kapag + verb + pronoun + rest

So:

• kapag sasakay tayo ng tren

You might also see more formal or emphatic versions such as:

• kapag tayo ay sasakay ng tren

That is grammatical, but the original sentence sounds more natural in everyday speech.