The -tion ending on a word signals that the word is a noun. We call -tion a suffix.
Any word that ends in -tion is a noun.
We can change a verb into a noun by adding -tion to the end of the verb. Look at these examples:
oppose becomes opposition
describe becomes description
react becomes reaction
introduce becomes introduction
consume becomes consumption
receive becomes reception
adopt becomes adoption
exclaim becomes exclamation
classify becomes classification
realize becomes realization
declare becomes declaration
translate becomes translation
Sometimes we use -sion to make a verb into a noun.
expand becomes expansion
convert becomes conversion
Whenever you see a word with a -tion or -sion ending, you can be sure that it is a noun. You can easiily change a verb into a noun by using the -tion or -sion ending.