Pakketeipen ligger ved bobleplasten.

Because Norwegian usually writes compound nouns as a single word.

• pakketeip = pakke
  • teip
• bobleplast = boble
  • plast

This is very common in Norwegian. Where English often uses two words, Norwegian often joins them:

• packing tape → pakketeip
• bubble wrap → bobleplast

A useful rule: the last part is the main noun, and the earlier part describes it. So pakketeip is a kind of teip, and bobleplast is a kind of plast.

In Norwegian, the is usually added to the end of the noun as a suffix.

Here:

• pakketeip → pakketeipen
• bobleplast → bobleplasten

So the -en ending is doing the job of the.

This is one of the biggest differences from English. Instead of a separate article before the noun, Norwegian often uses a definite ending on the noun itself.

In compounds, that ending goes on the very end of the whole word:

• pakketeip → pakketeipen
• not teipen pakke

The basic forms are:

• pakketeip
• bobleplast

These are the forms you would normally look up in a dictionary.

A small nuance: bobleplast is often used like a material noun, much like bubble wrap in English. Even so, Norwegian can still say bobleplasten when talking about the specific bubble wrap in the situation, for example the roll or sheet everyone already knows about.

Because Norwegian often uses a position verb when saying where something is.

Here, ligger is the natural choice for an object that is lying somewhere or resting somewhere.

English often just says is:

• The packing tape is by the bubble wrap

But Norwegian prefers something more specific:

• ligger = lies / is lying / is located lying down

So Pakketeipen ligger ved bobleplasten sounds more natural than using er in most everyday situations.

These three verbs are very important in Norwegian:

• ligger: lies, is lying, is resting horizontally or just placed somewhere
• står: stands, is standing upright
• sitter: sits, is attached, fixed, or seated

Examples:

• Boken ligger på bordet.
  The book is lying on the table.

• Flasken står på bordet.
  The bottle is standing on the table.

• Lappen sitter på esken.
  The note is attached to the box.

In your sentence, ligger suggests that the tape is lying there, not standing upright or attached to something.

Here, ved means something like:

• by
• next to
• beside
• near

It tells you that the packing tape is located close to the bubble wrap.

It does not necessarily mean direct contact, just close placement.

So ved is a very natural choice if one object is near another object.

Only if you mean something different.

• ved = by, next to, beside
• på = on, on top of

So:

• Pakketeipen ligger ved bobleplasten
  The tape is by the bubble wrap.

• Pakketeipen ligger på bobleplasten
  The tape is on the bubble wrap.

That is a real difference in meaning, not just a style difference.

Yes. This is a very normal main clause:

• Pakketeipen = subject
• ligger = verb
• ved bobleplasten = location phrase

So the pattern is:

• subject + verb + location

You can also move the location phrase to the front:

• Ved bobleplasten ligger pakketeipen.

That is also correct. When you do that, Norwegian keeps the verb in second position, so the subject comes after the verb. This is part of the normal verb-second pattern in Norwegian main clauses.

ligger is present tense.

So it means:

• lies
• is lying
• is located

The past tense is lå:

• Pakketeipen lå ved bobleplasten.
  The packing tape was lying by the bubble wrap.

A common perfect form is har ligget:

• Pakketeipen har ligget ved bobleplasten lenge.
  The packing tape has been lying by the bubble wrap for a long time.