Barren money is cash that isn’t earning any interest and just about everyone has at least a little barren money. Everyone needs at least some barren money for spending.
Most people that have a checking account don’t earn any interest on those funds. Some people do have interest checking accounts or reward accounts, but the majority have non-interest bearing checking accounts. Most checking accounts that don’t offer any interest also don’t have a minimum balance requirement, so people only keep spending money in their checking account and not more than they’ll need in any given month. If you do tend to keep a fair amount of money in your checking account then you should take a look at interest bearing checking accounts to make the most of your money. There will most likely be a minimum balance requirement to avoid a monthly fee, but if you keep your checking account well funded you may not have a problem with that.
Any money you keep on yourself or in your home is another example of barren money. Some people keep a private safe at home just in case there’s an emergency and they can’t get money from a bank for any reason. This was more popular in the past before ATMs were in existence. Now it makes more sense to keep any cash reserves in a high interest savings account.
People used to carry around more money before ATMs were around as well, but now as soon as you run low you can run out to an ATM for quick cash. Even more, there’s very few instances where you have to have cash to pay for goods or services. Most establishments take credit or debit cards making carrying around cash even more obsolete. ATMs have greatly reduced the need to have a large amount of barren money at any time.