SELECT CONVERT(VARCHAR(10), GETDATE(), 110) what is the meaning of 110 here?

That number indicates Date and Time Styles

You need to look at CAST and CONVERT (Transact-SQL). Here you can find the meaning of all these Date and Time Styles.

Styles with century (e.g. 100, 101 etc) means year will come in yyyy format. While styles without century (e.g. 1,7,10) means year will come in yy format.

You can also refer to SQL Server Date Formats. Here you can find all date formats with examples.