Sakrićemo ukrase.

This is a normal Serbian future-tense pattern. The future is formed with the auxiliary hteti in its short form plus the infinitive.

With sakriti, you can say:

Mi ćemo sakriti ukrase.
or

Sakrićemo ukrase.

When the infinitive comes before the short auxiliary, the -ti is dropped and the forms join into one word:
sakriti + ćemo → sakrićemo

So sakrićemo is not a different tense or meaning; it is just the standard fused form.

It is not stated separately, because Serbian often leaves subject pronouns out when the verb already makes the subject clear.

In sakrićemo, the ending -ćemo already tells you it means we will.
If you want extra emphasis, you can add the pronoun:

Mi ćemo sakriti ukrase.

But in everyday Serbian, leaving out mi is very common.

The dictionary form is sakriti, meaning to hide.

So the sentence is built from:

sakriti = to hide
sakrićemo = we will hide

Because ukrase is the accusative plural, which is used for the direct object of the verb.

Here, the thing being hidden is the decorations, so ukrasi changes to ukrase.

Basic forms:

• ukras = decoration
• ukrasi = decorations, nominative plural
• ukrase = decorations, accusative plural

Since hide what? → decorations, Serbian uses the accusative: ukrase.

Yes. Sakriti is perfective. That means it presents the action as a completed whole: to hide something successfully / to get it hidden.

So Sakrićemo ukrase suggests a completed future action: we will hide the decorations.

If you used an imperfective form like skrivaćemo, it would sound more like:

• we will be hiding
• we will hide repeatedly
• the action is ongoing rather than seen as completed

So aspect does matter, and sakriti is the natural choice when you mean a single completed act of hiding them.

Yes. Serbian word order is fairly flexible.

These are all possible, with slightly different emphasis:

Sakrićemo ukrase.
Mi ćemo sakriti ukrase.
Ukrase ćemo sakriti.

The basic meaning stays the same, but the focus can shift.
For example, Ukrase ćemo sakriti puts more emphasis on the decorations.

Serbian has no articles like the or a/an, so ukrase can mean:

• the decorations
• decorations
• sometimes even some decorations

The exact meaning depends on context. In many situations, English will naturally translate it as the decorations, but Serbian itself does not mark that with an article.

A rough pronunciation is sa-KRI-će-mo.

The letter ć is a soft consonant, somewhat like a very soft ch/t sound. It is softer than č.

So:

• sa = like sa in supper
• kri = roughly kree
• će = a soft tye/che-like sound
• mo = mo

A rough English-style approximation would be sah-KREE-tyeh-mo, but that is only approximate.