How to understand "for immediate consumption" term?
It's not generally about food safety or even quality. That phrase refers to the type of license the seller of the food item has. So the phrase has a legal meaning, which may have nothing to do with the food.

In some jurisdictions, grocery stores have different regulations and zoning than restaurants. So, one way to differentiate between grocery stores and restaurants is that food sold in restaurants is for immediate consumption. Some packaged food may only be sold to restaurants, or the labeling is different for packages destined for restaurants. Some information may be required on labels destined for grocery stores, which isn't required on labels for restaurant packages. Restaurant packages may be labeled "for immediate consumption".

Such rules are often frequently ignored, and regulations can change faster than labels. 

In the US, a more common way to see it on packages is "for foodservice use only".