language
The Italian word 'lingua' is used in a similar way to the English word 'language'. It refers to a system of communication, either spoken or written, used by a particular group of people. For example, 'Che lingua parli?' means 'What language do you speak?'.
The Italian language is beautiful.
This sentence represents a common personal opinion about languages, in this case the speaker is expressing a positive opinion about the Italian language, referring to it as 'beautiful'.
I am learning the French language.
In this instance, the speaker is using 'lingua' to communicate the active process of learning the French language. 'Sto' is the first person singular present tense of 'stare', which in this context means 'am'. 'Imparando' is the present participle of 'imparare', which means 'learning'.
A dog's tongue is warm.
This sentence features the other common meaning of 'lingua', which is 'tongue'. Here, the speaker is commenting on the physical characteristic of a dog's tongue, noting that it is 'warm'.