Bitcoin is an electronic asset. It is not money or electronic cash. Yes, you can use Bitcoin to pay for something in the same way as you can trade your car for a cat.
Recently some payment systems, for example Stripe, dropped Bitcoin as a method of payment. Stripe correctly states that Bitcoin is an asset and not a currency.
If you measure the value of a single Bitcoin against a real currency, for example the us$ then the value of a single Bitcoin can vary by 25% or 10% or 30% even in a single day. So, the measured value of Bitcoin is unstable. (The value depends greatly on the number of people buying and the number of people selling, this fluctuates greatly and causes instability in value)
If you buy or sell Bitcoin today you will find that the actual transaction takes too long. This delay causes wild fluctuations in the us$ price you purchased (or sold) your Bitcoin.
The core issue and problem with crypto currencies in general are that society (us the people) are not protected from criminals, tax evaders and other nefarious problems related to a non regulated and controlled “empty” or valueless asset.
Bitcoin is not backed up by any real value as the actual value of Bitcoin is not under written by anything other than hype and hysteria. It is a valuable asset in as much as the air inside a jar is an asset and Bitcoin is only worth as much as someone else is willing to pay for it.
If you are a newbie and interested in Bitcoin, you can read more here: https://en.wikipedia.org/wiki/Bitcoin