Leave travel allowance can be claimed against any travel done with family, this is restricted to travel in India.
LTA can be claimed only twice in a block of 4 years. We are currently on the 1st Jan 2018- 31 Dec 2022 block. You can claim two journeys against your LTA within this period.
Submit all the boarding passes in case of flights, travel tickets and bills to your company. You can see the total allowance you've received in your Form 16.
LTA is an allowance that your employer can give you. It cannot be claimed in the tax return directly. If you've shared receipts with your company, you'll see it in your Form 16.