Masa este în mijlocul camerei.

Because masa means the table, while masă means a table.

Romanian often puts the definite article at the end of the noun instead of using a separate word like English the.

• masă = a table
• masa = the table

So Masa este în mijlocul camerei starts with the table.

Este means is. It is the 3rd person singular form of the verb a fi (to be).

So:

• masa = the table
• este = is

Together: Masa este... = The table is...

In Romanian, este can sometimes be omitted in informal speech, but in a basic learner sentence like this, keeping it is completely normal and clear.

Because în mijlocul means in the middle of.

Here is the breakdown:

• în = in
• mijloc = middle
• mijlocul = the middle

In Romanian, when you say in the middle of something, you normally use în mijlocul + noun.

So:

• în mijlocul camerei = in the middle of the room

This is a fixed, very common structure.

Because after mijlocul you need the genitive form, which often corresponds to English of the...

So:

• camera = the room
• camerei = of the room

That is why:

• în mijlocul camerei = in the middle of the room

This is one of the most important grammar points in the sentence. Romanian often changes the ending of a noun after words that mean something like of.

Because Romanian often expresses of through the genitive case instead of using a separate word.

In English:

• the middle of the room

In Romanian:

• mijlocul camerei

There is no separate word for of here. Instead, Romanian shows that relationship by changing camera to camerei.

It is singular.

• camera = the room
• camerei = of the room

If it were plural, the form would be different:

• camere = rooms
• camerelor = of the rooms

So în mijlocul camerei clearly means in the middle of the room, not of the rooms.

Yes, Romanian word order is somewhat flexible.

The neutral, standard order is:

• Masa este în mijlocul camerei.

But you could also say:

• În mijlocul camerei este masa.

This gives more emphasis to the location, something like In the middle of the room is the table.

For a learner, the original version is the best one to use first.

A few pronunciation notes:

• în contains â/î, a Romanian vowel that does not exist in standard English. It is a central sound, somewhat deep and tight in the mouth.
• mijlocul is roughly pronounced meezh-LO-kool.

A rough guide for the whole sentence:

• Masa este în mijlocul camerei
• MA-sa YES-te ïn meezh-LO-kool ka-ME-rey

This is only approximate, but it can help at first.

Because -ul is the masculine/neuter singular definite article attached to the noun.

• mijloc = middle
• mijlocul = the middle

So Romanian is doing the same thing here as with masa:

• masă → masa
• mijloc → mijlocul

The article is added to the end of the noun.

Yes. Masă is a feminine noun.

That is why its definite singular form is:

• masă → masa

Romanian noun gender affects articles and some adjective forms, so it is useful to learn each noun together with its gender.

Yes. În centrul camerei means in the center of the room, and in many situations it is very close in meaning to în mijlocul camerei.

• în mijlocul camerei = in the middle of the room
• în centrul camerei = in the center of the room

În mijlocul often feels a bit more like in the middle, while în centrul can sound slightly more geometric or exact, but both are very common and natural.