Why the symbols matter more than the word
A parcel crossing a border is handled by people who may not read your language. The ISO 780 marks are pictorial for exactly that reason: a broken glass and a pair of up arrows mean the same thing in every warehouse. The word underneath helps whoever does share your language, which is why each sticker carries both.
What each mark means
Fragile. The contents break. Handle gently and do not drop.
This way up. The arrows point to the top of the parcel. Do not invert it.
Keep dry. Keep the parcel away from rain and damp storage.
Do not stack. Nothing may be placed on top of this parcel.
Keep away from heat. Keep the parcel out of direct sun and away from heaters. Candles, chocolate, cosmetics and anything with a wax or resin in it need this one.
Do not roll. Keep the parcel upright along its length. Do not turn it end over end or roll it along the floor.
Use no hooks. Do not lift the parcel with hooks. They tear the outer packaging and frequently whatever is directly under it.
Centre of gravity. Marks where the weight actually sits, so the parcel is lifted level instead of tipping out of someone’s hands.