nimotu ni teepu wo hatta.

荷物にテープを貼った。 is read:

にもつ に テープ を はった。

• 荷物 = にもつ
• テープ = テープ
• 貼った = はった

貼った is the plain past form of 貼る（はる）, which means to stick, to paste, or to attach something onto a surface.

So 貼った means stuck, pasted, or attached.

In this sentence, it means that tape was stuck onto the package/luggage.

With 貼る, the particle に marks the place or surface that something is attached to.

So in:

荷物にテープを貼った

• 荷物に = onto the package / on the luggage
• テープを = the tape
• 貼った = stuck

A good way to think of it is:

• を = the thing being attached
• に = the target surface

Because テープ is the direct object: it is the thing that gets stuck on something.

So:

• テープを貼る = to stick/apply tape
• 荷物に貼る = to stick something onto the package

Put together:

荷物にテープを貼る = to stick tape onto the package

Normally, no. That changes the roles of the words.

荷物をテープに貼った would sound like I stuck the package onto the tape, which is not the intended meaning.

In the original sentence:

• 荷物に = onto the package
• テープを = the tape that was used

So the original particle choice is important.

荷物 can mean luggage, baggage, package, parcel, or load, depending on context.

In this sentence, it most likely means something like:

• a package
• a parcel
• a piece of luggage

Japanese often leaves this kind of detail to context.

The subject is omitted.

Japanese often leaves out the subject when it is obvious from context. So this sentence could mean:

• I stuck tape on the package
• He stuck tape on the package
• She stuck tape on the package
• They stuck tape on the package

The sentence itself does not say who did it.

Because Japanese normally uses SOV word order: subject-object-verb.

So the verb usually comes at the end of the sentence.

Here the structure is roughly:

• 荷物に = onto the package
• テープを = tape
• 貼った = stuck

This is completely normal Japanese word order.

Yes, sometimes. Because the particles show each word’s role, Japanese word order is more flexible than English.

For example, this is also possible:

テープを荷物に貼った。

This still means the same thing. However, the verb 貼った normally stays at the end.

You usually do not know from the sentence alone.

Japanese nouns often do not mark singular vs. plural clearly. So:

• 荷物 could mean a package or packages
• テープ could mean tape or sometimes strips/rolls of tape, depending on context

You rely on context to know the exact number.

Yes. Both are read はった in the past tense, but the kanji are different.

• 貼る = to stick, paste, attach with adhesive
• 張る = to stretch, put up, spread, tighten, and some other meanings

For tape, 貼る is the normal kanji, because tape is something you stick onto a surface.

The polite past form is:

荷物にテープを貼りました。

The plain form in your sentence is:

荷物にテープを貼った。

So:

• 貼った = plain past
• 貼りました = polite past

Both mean the same thing, but 貼りました is more formal/polite.