guìzhòngwùpǐn yào zhuāngxiāng, yǐmiǎn fāshēng sǔnshī.

Here, 要 means need to / should / must.

So in 贵重物品要装箱, it does not mean valuable items want to be packed. It means:

• valuable items should be packed in a box
• valuable items need to be boxed

This kind of 要 is very common in instructions, notices, and practical advice.

Compare:

• 我要去中国。 = I want to go to China.
• 贵重物品要装箱。 = Valuable items must/should be boxed.

The meaning depends on context.

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

In this sentence, the real meaning is something like:

• 贵重物品要装箱
  = Valuable items should be packed = You should pack valuable items in a box

The person doing the action is not the main focus. The focus is the rule or instruction itself.

This is very common in notices and warnings. English often needs a subject, but Chinese often does not.

It can be understood as valuable item(s) in a general sense.

Chinese nouns usually do not show singular/plural the way English nouns do. So 贵重物品 can mean:

• valuable items
• valuable property
• valuables

The exact number comes from context.

If you need to make it clearly plural, you usually do it with context, numbers, or classifiers, not by changing the noun itself.

Both are possible, but 贵重物品 is more compact and natural in formal or practical writing.

• 贵重物品 = a fixed noun phrase, like valuables
• 贵重的物品 = items that are valuable, slightly more descriptive

In Chinese, 的 is often omitted when the modifier and noun form a tight, common combination. This is especially common in short labels, signs, warnings, and official language.

So:

• 贵重物品 sounds concise and standard
• 贵重的物品 is grammatical, but a little less compact

装箱 literally means put into a box / crate / case for packing.

It is a fairly practical, logistics-related verb. It suggests boxing up or packing into a container rather than just putting somewhere.

Compare:

• 装箱 = pack into a box/crate/case
• 放进箱子里 = put into a box

装箱 sounds more like a packaging or shipping instruction.

In this sentence, it is best understood broadly as:

• valuable items should be boxed
• valuable items need to be packed in a box

Chinese often does not mark the passive as explicitly as English does. So 要装箱 does not necessarily focus on who does it.

It could imply:

• you should box them
• they should be boxed

The important point is the requirement, not the agent.

以免 means in order to avoid, so as to avoid, or to prevent.

It introduces the undesirable result that you want to avoid.

Structure:

• A，以免 B
• Do A, so as to avoid B

In this sentence:

• 贵重物品要装箱，以免发生损失。
• Valuable items should be boxed to avoid loss/damage.

This word is a bit formal and is common in written instructions, notices, and official language.

They are similar, but 以免 is usually more formal and written.

• 以免 = formal, often used in notices/instructions
• 免得 = more common in everyday speech

Examples:

• 请提前出发，以免迟到。
  Formal: Please leave early so as to avoid being late.

• 快点出发，免得迟到。
  More conversational: Leave soon, or you'll be late.

In your sentence, 以免 fits the formal warning style very well.

Yes, it is natural, though it sounds formal.

• 发生 = to happen / occur
• 损失 = loss / damage

So 发生损失 literally means for loss to occur.

This kind of wording is common in formal written Chinese, especially in business, transport, insurance, shipping, and warnings.

Other possible expressions include:

• 避免损失 = avoid losses
• 遭受损失 = suffer losses
• 造成损失 = cause losses

The differences are:

• 发生损失 focuses on the event of loss occurring
• 遭受损失 focuses on someone suffering the loss
• 造成损失 focuses on causing the loss

Because 损失 can cover several related ideas depending on context:

• financial loss
• damage
• loss of property
• harm caused by mishandling

In a sentence about packing valuables, 损失 is intentionally broad. It can include:

• items being damaged
• items being lost
• monetary loss resulting from that

Chinese often uses broad nouns like this in formal instructions.

The structure is:

• 贵重物品 = topic / thing being discussed
• 要装箱 = should be boxed
• 以免发生损失 = so as to avoid loss occurring

So the pattern is:

• Noun phrase + 要 + Verb + 以免 + bad result

A simplified pattern would be:

• A 要 B，以免 C
• A should do B, in order to avoid C

This is a very common structure in formal advice and warnings.

The comma separates the main instruction from the purpose/result clause.

• 贵重物品要装箱 = main instruction
• 以免发生损失 = purpose: to avoid loss

In Chinese, punctuation is often used to clearly break up parts of a sentence, especially in formal writing. The comma here makes the sentence easier to read and shows that the second part explains why the first part should be done.

Yes, it is fairly formal and practical.

You might see this kind of sentence in:

• shipping instructions
• warehouse notices
• moving or storage guidelines
• customs/logistics documents
• cargo handling warnings

It sounds more like written instruction than casual conversation.

In everyday speech, someone might say something simpler, such as:

• 贵重物品最好装箱，免得弄坏。
• You’d better box valuable items, so they don’t get damaged.

Only if the meaning changes appropriately.

• 贵重物品 = valuables
• 行李 = luggage
• 东西 = things/stuff

If the warning is specifically about valuables, 贵重物品 is the best choice.

For example:

• 行李要装箱 = luggage should be packed in a box
• 东西要装箱 = things should be boxed

Those are broader and less precise. 贵重物品 specifically highlights items of high value.

Yes, it helps to see the sentence in words, not as one long string:

• 贵重物品 — guìzhòng wùpǐn
• 要 — yào
• 装箱 — zhuāngxiāng
• 以免 — yǐmiǎn
• 发生 — fāshēng
• 损失 — sǔnshī

A useful point: 贵重物品 is a four-syllable noun phrase made of:

• 贵重 = valuable
• 物品 = articles/items

Learning the sentence in chunks will make it much easier to understand and remember.