The term ‘parliamentary majority’ can have different meanings.
'Parliamentary majority' can mean that a party or coalition of parties must have the support of the majority of members in the House of Representatives to form government. This is also known as a government majority. With the support of more than half of the members in the House of Representatives, a government can use its parliamentary majority to pass its bills and carry out its policies. In Australia there are 151 seats in the House of Representatives and the number required to form government is 76 (half the total number of members plus 1).
‘Parliamentary majority’ can also be used to describe the number of seats the government has above those needed to form government. If a party won 90 seats at an election, but they only needed 76 to form government, you could say they have a parliamentary majority of 14 (90-76=14). This is the meaning parliamentary majority has in the British House of Commons.