In essence a payable is an obligation or a liability you’ve got against another party. This “party” can be your supplier, your employee, regulators, owners and so on. 

You buy goods, account them as your inventory and as a result, take up a commitment to pay for those goods. Unless you pay at the spot (which businesses rarely do), you account for the goods into inventory and a payable account alongside in the same amount. For an example let’s say you bought goods for 10,000, your accounting entry is as follows:

Db Inventory

Cr Accounts payable

Keep in mind three things:

1. Your inventory should have a separate ledger where you keep account for each item on its own prices, quantities and so on.
2. Your accounts payable are also never just one sum, but there ought to also be a separate ledger to keep track on all the amounts owed to each supplier or counterparty.
3. Both of those separate ledgers should match with the total amount on the balance sheet.

And that’s that. Now in case the counterparty is say your employee, the other side of the entry would be expenses:

Db Expense account

Cr Account payable to employees

I would say that a lot of the other entries, except the inventory one, are similar to the employee expense one. You account for the expense and related payable. One other entry that is similar to the inventory one though, is the one you do when you buy property. Instead of inventory you would then account for an asset account.

To summarize, a payable is you showing what you owe for the assets you own and the expenses you’ve made in your business.