Hon lägger en liten kniv bredvid tallriken och värmer maten i mikrovågsugnen.

Lägger is the present tense form of the verb lägga.

• lägga = to lay / to put
• lägger = puts / is putting

Since the sentence describes what she does, Swedish uses the present tense:

• Hon lägger ... = She puts ...

This is very similar to English puts rather than to put.

This has to do with gender and adjective agreement in Swedish.

• kniv is an en-word
• so the indefinite article is en
• the adjective liten matches an en-word in the singular

So:

• en liten kniv = a small knife

Compare:

• en liten bok = a small book
• ett litet hus = a small house

Notice that liten is a slightly irregular adjective:

• en liten
• ett litet
• små in the plural

Yes. It does not follow the most basic adjective pattern perfectly.

Many adjectives work like this:

• en stor bil
• ett stort hus
• stora bilar

But liten changes like this:

• en liten kniv
• ett litet barn
• små knivar

So a learner often has to memorize liten / litet / små as a special pattern.

Tallriken is the definite singular form: the plate.

• en tallrik = a plate
• tallriken = the plate

Swedish often uses the definite form when the object is understood to be a specific one in the situation. In this sentence, it is not just any plate, but a particular plate.

This definite ending is very common with en-words:

• en bok → boken
• en stol → stolen
• en tallrik → tallriken

Bredvid means beside / next to.

In this sentence:

• bredvid tallriken = beside the plate / next to the plate

A useful thing to notice is that Swedish does not need an extra word like English sometimes does. You simply say:

• bredvid tallriken
• not something like bredvid av tallriken

More examples:

• bredvid huset = next to the house
• bredvid mig = next to me

Värmer is the present tense of värma, meaning to heat / warm.

• värma = to heat
• värmer = heats / is heating

So:

• hon värmer maten = she heats the food

Like many Swedish verbs, the present tense is formed with -r:

• bo → bor
• läsa → läser
• värma → värmer

Maten means the food.

• mat = food
• maten = the food / the meal / the food in question

Swedish often uses the definite form where English may simply say food, especially when talking about a specific meal or the food being handled right now.

So in this sentence, maten probably means the specific food she is heating.

Compare:

• Jag gillar mat. = I like food.
• Jag värmer maten. = I’m heating the food.

The preposition i means in.

So:

• i mikrovågsugnen = in the microwave oven

This is natural because the food goes inside the microwave, not on top of it.

Also, mikrovågsugnen is definite:

• en mikrovågsugn = a microwave oven
• mikrovågsugnen = the microwave oven

In everyday English, we often just say the microwave, but Swedish commonly uses the full word mikrovågsugn.

It is a compound noun, which is very common in Swedish.

It is made from:

• mikrovåg = microwave
• ugn = oven
• -en = the definite ending

So:

• mikrovågsugn = microwave oven
• mikrovågsugnen = the microwave oven

The s in the middle is a linking sound that often appears in Swedish compounds. You do not translate it separately.

Because both verbs share the same subject.

The sentence has two actions joined by och:

• Hon lägger en liten kniv bredvid tallriken
• och värmer maten i mikrovågsugnen

The subject hon applies to both verbs, so Swedish does not need to repeat it.

English works the same way:

• She puts a small knife beside the plate and heats the food in the microwave.

You could repeat the subject in some contexts, but it is usually unnecessary here.

The basic word order is:

Subject + Verb + Object/Other information

So here:

• Hon = subject
• lägger = verb
• en liten kniv = object
• bredvid tallriken = place
• och värmer = second verb phrase
• maten = object
• i mikrovågsugnen = place

So the structure is very normal and straightforward.

A rough pattern is:

Hon + lägger + en liten kniv + bredvid tallriken + och + värmer + maten + i mikrovågsugnen

Swedish often chooses different verbs for putting things depending on position.

• lägga is used when something is placed lying down or in a horizontal position
• ställa is often used when something is placed standing
• sätta is often used for setting something in a seated/fixed position

A knife is normally thought of as lying on the table, so lägger is the natural choice.

Examples:

• lägga en bok på bordet = put a book on the table
• ställa en flaska på bordet = put a bottle on the table
• sätta sig = sit down

This is one of those things that can feel unusual to English speakers, because English often just uses put for all of them.

Yes, in natural English that is often the best translation.

Literally, mikrovågsugnen means the microwave oven, but English speakers usually shorten this to the microwave.

So:

• värmer maten i mikrovågsugnen
  can naturally be translated as
• heats the food in the microwave

Both are correct, but in the microwave sounds more everyday in English.

Because Swedish simple present often covers both meanings:

• she puts
• she is putting

and

• she heats
• she is heating

So hon lägger can mean either she puts or she is putting, depending on context.

Swedish usually does not need a separate progressive form the way English does.

That means:

• Hon lägger en liten kniv ... can describe a present action
• Hon värmer maten ... can also describe an action happening now

Context tells you whether English should use puts or is putting, heats or is heating.