Much of the basic vocabulary involved with subtraction is introduced in year 1, including these terms:
take away, subtract, how many are left, less than, what is the difference between, more than.
The minus (-) sign is also introduced.
As with addition, at this age most of the work will be done orally. All kinds of opportunities arise where simple subtraction questions can be posed.
A number line is useful so that children can see the movement down the line as numbers are subtracted. Schools use number lines a great deal and I strongly recommend that you make one at home. One way to do this is to have a line of string with eleven pegs on, each peg holding a sheet with each number on from zero to 10.
Free Y1 maths worksheets: Understand ‘Take … from …’ (pg 1)