Tom boort een tweede gat, zodat de plank steviger hangt.

Boort is the third-person singular present tense of boren, which means to drill.

• ik boor = I drill
• jij boort = you drill
• Tom boort = Tom drills

So Tom boort means Tom drills.

Een tweede gat means a second hole: it introduces another hole, not a specific already-identified one.

• een tweede gat = a second hole
• het tweede gat = the second hole

So if you are simply saying Tom drills another hole, een tweede gat is natural.

Also note that gat is a het-word, so if it were definite, it would be het gat.

Dutch ordinal numbers like eerste, tweede, derde, etc. normally appear with -e when used before a noun.

So:

• de tweede dag = the second day
• een tweede gat = a second hole

This is just the normal form of the ordinal adjective here.

Zodat means so that or with the result that.

In this sentence, it introduces the result of the action:

• Tom drills a second hole,
• so that / with the result that the shelf hangs more securely.

It often connects a cause/action in the main clause to a result in the subordinate clause.

Because zodat introduces a subordinate clause, and in Dutch subordinate clauses the conjugated verb usually goes to the end.

So:

• main clause: Tom boort een tweede gat
• subordinate clause: zodat de plank steviger hangt

That final position of hangt is completely normal after zodat.

This is about Dutch noun gender and articles.

• plank is a de-word → de plank
• gat is a het-word → het gat

But with the indefinite article, both de-words and het-words use een:

• een plank
• een gat

So in the sentence, you can see the gender of plank because it has de, but you cannot see the gender of gat because it has een.

Steviger is the comparative form of stevig.

• stevig = firm, sturdy, secure
• steviger = firmer, sturdier, more securely

In this sentence, a very natural English meaning is something like:

• more securely
• more firmly
• more sturdily

Even though it looks like an adjective, in English we often translate it adverbially here.

Because steviger is not directly describing the noun plank. It is part of the predicate with hangt.

So this is roughly:

• the shelf hangs more securely

not:

• the sturdy shelf hangs

Compare:

• de stevige plank = the sturdy shelf
• de plank hangt steviger = the shelf hangs more securely / more firmly

So steviger is the comparative form used with the verb, not an attributive adjective before the noun.

Because the subject of the subordinate clause is de plank, which is singular.

• de plank hangt = the shelf hangs
• de planken hangen = the shelves hang

So hangt agrees with singular de plank.

Good question. Dutch uses hangen more broadly than English sometimes does. It can be used for things that are mounted, suspended, or attached in a way that leaves them hanging on something.

So de plank hangt steviger may sound a bit literal if translated word-for-word, but the intended meaning is natural in Dutch: the plank/shelf is attached in a more secure way.

Depending on context, English might say:

• the shelf is more secure
• the shelf hangs more securely
• the board is fixed more firmly

In Dutch, a subordinate clause introduced by a conjunction like zodat is often separated by a comma, especially when it follows the main clause.

So:

• Tom boort een tweede gat, zodat de plank steviger hangt.

This is standard punctuation.

Yes. This is standard main clause word order in Dutch: the finite verb is in the second position.

Structure:

• Tom = subject
• boort = finite verb
• een tweede gat = object

So this is a normal V2 sentence:

• Tom boort een tweede gat.

Yes, but the meaning shifts slightly.

• een tweede gat = a second hole
• nog een gat = another hole / one more hole

In many contexts they are close, but een tweede gat emphasizes that it is specifically the second one. Nog een gat is a bit less precise and just means an additional hole.