May isang tiket pa ako para sa tren.

A very literal breakdown is:

• May = there is / there exists
• isang tiket = one ticket
• pa = still / yet / another / more
• ako = I / me
• para sa tren = for the train

So the structure is roughly There is still one ticket with me for the train, which becomes natural English as I still have one ticket for the train.

Not exactly.

Filipino often expresses possession with an existence pattern instead of a direct verb like English have. So:

• May tiket ako literally works like There is a ticket with me
• but the natural English meaning is I have a ticket

So in this sentence, may is what makes the possession idea possible.

Because isa becomes isang when it directly modifies a noun.

The -ng is a linker that connects the number to the noun:

• isa = one
• isang tiket = one ticket

This is very common:

• isang libro = one book
• isang tao = one person

Pa is a very common small word that adds the idea of:

• still
• yet
• more
• another

In this sentence, it most likely gives one of these meanings:

• I still have one ticket for the train
• I have one more ticket for the train

So pa is the word that adds the sense of continuation or extra quantity.

Because Filipino word order often works differently from English.

In sentences like this, the existence or predicate part often comes first, and short pronouns like ako come after it. So:

• May isang tiket pa ako... is natural

English wants I first, but Filipino often does not.

After may, the noun normally comes without ang.

So you say:

• May tiket ako

not:

• May ang tiket ako

That is just how the may construction works in Filipino.

Para sa means for or intended for.

So para sa tren means for the train.

It tells you what kind of ticket it is: a ticket meant to be used for the train.

Also, para is commonly followed by sa before a noun phrase, so para sa tren is the normal form.

Yes, that is also natural.

May, mayroon, and meron are related forms. A useful difference is:

• may must be followed directly by a noun: May tiket ako
• mayroon/meron can be used more independently: Mayroon akong tiket

So both of these work:

• May isang tiket pa ako para sa tren
• Mayroon pa akong isang tiket para sa tren

The meaning is basically the same.

It could mean either one, depending on context.

Because of pa, the sentence may suggest:

• still: you continue to have one ticket left
• one more / another: you have an extra ticket

So context decides the best English translation.

No, tren is a borrowed word, ultimately from Spanish.

That is very common in Filipino. Many everyday words came from Spanish or English, but they are now normal Filipino vocabulary. So tren is simply the standard Filipino word for train.