winter
Winter is the German word for the season winter. It is used in the same way as in English, to refer to the coldest season of the year, typically occurring between autumn and spring.
The winter is cold.
This is a straightforward phrase describing the characteristics of winter. Winter, being a season, is referred to as 'der Winter' in German, following the definite article 'der' and 'ist' is the verb to be, 'kalt' means cold.
We often have snowball fights in winter.
This sentence is sharing a common activity during winter. The preposition 'im' is a contraction of 'in' (in) and 'dem' (the) used before masculine and neutral nouns in Dativ case, 'oft' translates to often, and 'Schneeballschlacht' is the German term for snowball fight.
My favorite season is winter.
This sentence is stating a personal preference for winter as a favorite season. 'Lieblingsjahreszeit' in German is a compound noun made up of 'Liebling' (favorite) and 'Jahreszeit' (season), 'ist' is the verb to be.