Zagladite stijenku.

Here it is most naturally the imperative: a command meaning smooth ... or make ... smooth.

More specifically, zagladite is the 2nd person plural imperative of zagladiti.

That means it can be used:

• to speak to more than one person: You all, smooth the surface
• to speak to one person formally/politely: Please smooth the surface

So Croatian -te often corresponds to English you all or polite you in commands.

Because it is the direct object of the verb, so it goes into the accusative case.

The base form is stijenka. In this sentence, you are doing the action to it, so you need the accusative singular:

• nominative: stijenka
• accusative: stijenku

This is a very common pattern for feminine nouns ending in -a:

• knjiga → knjigu
• lopata → lopatu
• stijenka → stijenku

So Zagladite stijenku literally has the structure Smooth the sidewall/surface.

Stijenka usually does not mean an ordinary house wall in the everyday sense. For a normal wall, Croatian more often uses zid.

Stijenka often means something like:

• a sidewall
• an inner wall
• a surface layer
• the wall of a container, cavity, organ, vessel, etc.
• in technical contexts, a thin wall or wall-like surface

So this sentence sounds quite natural in:

• technical instructions
• medical/scientific descriptions
• craft/workshop language
• manufacturing or construction contexts

If you were talking about smoothing a normal wall in a room, zid might be more likely.

The prefix za- helps make the verb perfective.

A useful contrast is:

• gladiti = to smooth, stroke, iron, keep smoothing
• zagladiti = to smooth out, make smooth, finish smoothing

So zagladiti focuses more on the action as a completed result.

In instructions, that is very common, because commands often focus on getting a result:

• Cut it
• Attach it
• Smooth it

Croatian often uses perfective verbs that way.

Formally, zagladite can also match the 2nd person plural present form.

However, in a sentence like Zagladite stijenku., especially in instructions, it is understood as an imperative command.

Also, because zagladiti is a perfective verb, its present-tense forms usually do not describe an ongoing present action the way English does. They often have a future or completed-event feel depending on context.

So in practice, here the intended reading is clearly:

• Smooth the surface not
• You are smoothing the surface

It can be either:

• more than one person: you all smooth the surface
• one person formally: please smooth the surface

Croatian uses the same -te ending for both.

So without more context, zagladite does not tell you by itself whether the speaker is:

• addressing a group, or
• speaking politely to one person

Because Croatian usually does not need subject pronouns when the verb ending already shows the person and number.

The ending -te already tells you this is addressed to:

• you plural, or
• you formal singular

So vi is unnecessary unless you want extra emphasis, contrast, or clarity.

For example:

• Zagladite stijenku. = normal, natural
• Vi zagladite stijenku. = more emphatic, like you do it

Yes. Croatian word order is more flexible than English.

The neutral order here is:

• Zagladite stijenku.

But you could also say:

• Stijenku zagladite.

That version puts extra focus on stijenku. It may sound more emphatic or contrastive, depending on context.

In step-by-step instructions, though, verb + object is very natural and common.

In Croatian, commands often end with a period, especially in:

• instructions
• manuals
• recipes
• textbooks
• technical writing

So Zagladite stijenku. is perfectly normal for an instructional style.

An exclamation mark would make it sound stronger, more emotional, or more urgent:

• Zagladite stijenku!

That is possible, but less neutral.

The dictionary form is zagladiti.

The imperative forms are built from the verb stem:

• (ti) zagladi = smooth ...! informal singular
• (vi) zagladite = smooth ...! plural or formal
• (mi) zagladimo = let’s smooth ...

So this sentence uses the plural/formal imperative form.

That is why you see:

• zagladi for one informal person
• zagladite for several people or one formal person