Tryggingarféð og uppsagnarfresturinn standa í samningnum um leiguhúsnæðið.

Because the subject is plural: Tryggingarféð og uppsagnarfresturinn = the security deposit and the notice period.

In Icelandic, the verb agrees with the subject in number:

• stendur = singular
• standa = plural

So:

• Tryggingarféð stendur... = The security deposit is...
• Uppsagnarfresturinn stendur... = The notice period is...
• Tryggingarféð og uppsagnarfresturinn standa... = The security deposit and the notice period are...

Literally, standa means to stand, but in this sentence standa í is idiomatic.

Here it means something like:

• be stated in
• be included in
• appear in

So standa í samningnum means to be written in the contract or to be included in the contract, not physically stand inside it.

This is a very common thing in Icelandic: a verb may keep its basic meaning in some contexts, but in a fixed phrase it takes on a more idiomatic sense.

Because í can take either:

• dative for location: in, inside, within
• accusative for movement into something

Here there is no movement. The information is in the contract, so Icelandic uses the dative:

• í samningnum = in the contract

Compare:

• Það stendur í samningnum. = It is written in the contract.
• Ég setti það í samninginn. = I put it into the contract.

So:

• location/state → dative
• motion into → accusative

The base form is samningur = contract.

Here it appears as samningnum, which is:

• singular
• definite
• dative

A rough breakdown:

• samningur = a contract
• samningurinn = the contract
• samningnum = in/to/from the contract, depending on the preposition

In this sentence, í requires the dative because it expresses location, so samningurinn changes to samningnum.

Here um means about, concerning, or for.

So:

• samningurinn um leiguhúsnæðið = the contract about/concerning the rental housing
• in more natural English: the lease agreement for the rental property

The preposition um takes the accusative, which is why the noun appears as leiguhúsnæðið.

It is a compound noun:

• leigu- = rental, rent-related
• húsnæði = housing, premises, accommodation, property
• -ið = the definite article (the)

So leiguhúsnæðið means:

• the rental housing
• the rented property
• the rental premises

Depending on context, English may translate it more naturally as the rental property or the apartment/house being rented.

Because Icelandic usually attaches the definite article directly to the noun instead of using a separate word like English the.

So:

• tryggingarfé = security deposit
• tryggingarféð = the security deposit

and:

• uppsagnarfrestur = notice period
• uppsagnarfresturinn = the notice period

Since both items are specific, both are definite.

They are in the nominative, because they are the subject of the sentence.

The subject is: Tryggingarféð og uppsagnarfresturinn

And the verb is: standa

Since they are the things that stand / are stated, they appear in the nominative case.

Because they are different genders and have different noun patterns.

• tryggingarfé is neuter
• uppsagnarfrestur is masculine

The suffixed definite article changes depending on gender and form:

• neuter often has -ið
• masculine often has -inn or -urinn, depending on the noun

So:

• tryggingarféð = the security deposit
• uppsagnarfresturinn = the notice period

This difference is normal and very common in Icelandic.

Uppsagnarfrestur means notice period or period of notice.

It is also a compound:

• uppsögn = termination, cancellation, notice
• frestur = period, deadline, time limit

Together, uppsagnarfrestur is the amount of time that must pass after giving notice before the agreement actually ends.

In rental contexts, it usually means the legally or contractually required notice period for ending the lease.

Yes. It is a normal way to list two contract terms.

Icelandic often works much like English here:

• The security deposit and the notice period are stated in the contract.

There is nothing unusual about putting those two nouns together with og.

If the speaker wanted to emphasize one part more strongly, word order in a larger sentence could change, but this version is straightforward and natural.

Yes. A very literal translation might sound slightly stiff in English.

More natural English versions could be:

• The security deposit and the notice period are stated in the lease agreement.
• The contract for the rental property states the security deposit and the notice period.
• The security deposit and notice period are included in the rental agreement.

So even though standa í literally relates to standing, the natural English translation is often be stated in or be included in.

In this context, yes, very often.

Literally it is something like:

• the contract concerning the rental housing/property

But in natural English, that is usually just:

• the lease agreement
• the rental contract
• the tenancy agreement

So a learner should understand the literal structure, but also know that English often uses a simpler legal term.