siteibukuro wo tukaimasu.

It is usually read していぶくろ.

• 指定 = してい, meaning designated / specified
• 袋 = ふくろ, meaning bag

In compounds, ふくろ often becomes ぶくろ, so 指定袋 becomes していぶくろ.

を marks the direct object of the verb.

In 指定袋を使います, the thing being used is 指定袋, so を shows that bag is the object of 使います.

A natural breakdown is:

• 指定袋 = designated bag
• を = object marker
• 使います = use / will use / use politely

使います is the polite form of 使う.

• 使う = plain/dictionary form
• 使います = polite form

Japanese often uses the polite form in:

• signs
• instructions
• public notices
• formal speech

So this sentence sounds appropriate for something like a rule, notice, or instruction.

It is the non-past form, so the exact time depends on context.

It can mean things like:

• use
• will use
• are going to use

In a notice or rule, it often has the sense of:

• Use designated bags
• Please use designated bags
• You must use designated bags

Japanese non-past forms are broader than English present tense, so context matters a lot.

Japanese often leaves out the subject when it is obvious from context.

So 指定袋を使います does not explicitly say who uses the bag. Depending on the situation, it could mean:

• I use the designated bag
• We use designated bags
• You should use the designated bag
• People use designated bags

On a sign or in instructions, the implied subject is often you.

Not directly, but it can function like an instruction depending on context.

Grammatically, it is a polite statement: (someone) uses/will use designated bags.

However, on signs and notices, Japanese often uses polite statements to express rules or instructions. So it may feel like:

• Use designated bags
• Please use designated bags

A more explicit request would be:

• 指定袋を使ってください。 = Please use designated bags.

It is a compound noun meaning something like designated bag, specified bag, or official bag.

In real life, this often refers to a bag that has been officially approved for a specific purpose, such as:

• municipal garbage bags
• recycling bags
• bags required by a school, building, or organization

So the exact English translation depends on the context, but designated bag is a good basic understanding.

Japanese does not use articles like the or a/an.

So 指定袋 by itself can mean:

• a designated bag
• the designated bag
• designated bags

The exact meaning depends on context.

For example:

• in a general rule, it may mean designated bags
• in a specific situation, it may mean the designated bag

Japanese nouns usually do not show singular vs. plural unless the speaker wants to make that clear.

So 指定袋 could mean:

• a designated bag
• designated bags

You decide from context. In English, you usually must choose singular or plural, but Japanese often leaves it unstated.

Yes, 指定の袋 is possible and means the designated bag or a specified bag.

But there is a small nuance:

• 指定袋 is a tighter compound noun and often sounds like a fixed term
• 指定の袋 sounds a little more descriptive, like the bag that has been designated

In many practical contexts, especially on signs or official notices, 指定袋 is very natural.