Ek plak die pleister op my vinger.

Here plak means to stick / to put on / to apply.

So Ek plak die pleister op my vinger means that the speaker is sticking or applying the plaster onto the finger.

A useful thing to know is that plak often has the basic idea of sticking something onto something.

Die means the, while 'n means a / an.

So:

• die pleister = the plaster
• 'n pleister = a plaster

This sentence uses die pleister, which suggests a specific plaster is meant.

Compare:

• Ek plak die pleister op my vinger. = I put the plaster on my finger.
• Ek plak 'n pleister op my vinger. = I put a plaster on my finger.

No. In Afrikaans, die does not change for gender.

That is one of the nice simple features of Afrikaans:

• die man = the man
• die vrou = the woman
• die kind = the child

Afrikaans nouns do not use grammatical gender in the article the way some other Germanic languages do.

This is the normal word order for a simple main clause in Afrikaans:

• Ek = subject
• plak = verb
• die pleister = object
• op my vinger = prepositional phrase

So the basic structure is:

Subject + verb + object + place/prepositional phrase

That makes this sentence very natural and straightforward.

In Afrikaans, possessives are simple before a noun:

• my vinger = my finger
• jou hand = your hand
• sy arm = his arm
• haar been = her leg

You just put the possessive word directly before the noun. There is no apostrophe and no agreement ending here.

So my vinger is simply the normal way to say my finger.

Op usually means on or onto.

In this sentence, the plaster is being placed on the finger, so op is the natural choice:

• op my vinger = on my finger

For an English speaker, this is fairly direct and matches English well.

Usually, no. In the present tense, Afrikaans verbs are much simpler than English verbs.

You get:

• Ek plak = I stick / I am sticking
• Jy plak = you stick / are sticking
• Hy plak = he sticks / is sticking
• Ons plak = we stick / are sticking

The verb form plak stays the same.

That is a very common feature of Afrikaans verbs.

Afrikaans often uses the simple present where English might use either:

• I put
• I am putting

So Ek plak die pleister op my vinger can work for an ongoing present action, depending on context.

Afrikaans does have ways to be more explicitly progressive, but in ordinary speech the simple present is often enough.

Here pleister means a plaster in the medical sense, or bandage / adhesive bandage depending on the variety of English you use.

Afrikaans pleister can also mean plaster in other contexts, such as building material, but in this sentence op my vinger makes the medical meaning clear.

A common past-tense version is:

Ek het die pleister op my vinger geplak.

This uses the usual Afrikaans past-tense pattern:

• het
  • past participle
• geplak = stuck / put on

So literally the structure is:

Ek het ... geplak = I stuck / I put on

Yes, in everyday speech you may also hear sit used in the sense of put:

• Ek sit die pleister op my vinger.

That is also natural Afrikaans.

The difference is roughly this:

• plak emphasizes sticking / attaching
• sit emphasizes putting / placing

Because a plaster is something you stick onto the skin, plak is especially appropriate here.