The noun 'rice' is an uncountable noun, a word for a food substance. Units of rice are expressed as grains of rice, cups of rice, bags of rice, etc.
Plural forms for some substances are reserved for 'kinds of' or 'types of' such as 'a dish of two rices' means two types of rice used, basmati and wild.
countable
The noun 'daytime' is an uncountable noun.
The noun sheet is a countable noun. The plural form is sheets.
The noun skill is a countable noun; a skill or many skills.
The term "security" can be both countable and uncountable, depending on the context. As an uncountable noun, it refers to the state of being safe or protected, such as in phrases like "personal security." However, when referring to specific financial instruments or measures, such as stocks or bonds, "securities" is used as a countable noun. Thus, the context determines whether "security" is countable or uncountable.
Transport is both countable and uncountable as a noun.
The noun 'steel' is an uncountable (mass) noun, a word for a substance.
Shark is a countable noun.
countable
Countable
The noun 'daytime' is an uncountable noun.
The noun 'animal' is a countable noun. The plural form is animals.
Prawn - prawns is the plural - is a countable noun
The word 'violence' is an uncountable noun.
Pasta is a countable noun
Countable
The gerund painting is a countable noun, as in "There are 12 paintings in this room."