what do we mean by traveler cheque>?

Answer 1

Traveler's checks are similar to a bank check. They are guaranteed to be good by the issuing bank (because you pre-paid for them). If they are stolen you can get them replaced providing you can provide the serial numbers of the ones stolen.

They are secure in that you sign them first at the bank and then again a second time in front of the person your spending them with. This is a proof point that they belong to you.

They are essentially the same as cash. They were in vogue for travel 20-30 years and further back. By and large they are falling out favor, since everyone uses credit cards and ATM machines now.