Since blockchain is public.. can someone tell how
Yes. Simply paste your bitcoin adress into a block explorer such as http://blockchain.info

For example, this adress has 200$ pending -> https://blockchain.info/address/1Lx4aebbGAUA2ASuYBoiAC2akutzpZQMzb Or, 0.025631 BTC

You can also add a watch-only adress in bitcoin-core / electrum to keep track of balances from certain adresses.