Simply put
The five steps: (1) identify the contract with the customer, (2) identify the performance obligations in it, (3) determine the transaction price, (4) allocate the price to the performance obligations, (5) recognize revenue on satisfying each obligation or over the period it is satisfied.
In a simple sale from a shop the steps happen in a single moment. They matter in complex contracts: a device with maintenance, a project lasting years, or a subscription.
Example
A software company signs a contract to sell a program, training and one year of support: it identifies the contract, then three performance obligations, then the total price, then allocates it among them, recognizing the program's revenue on delivery, the training when it is provided, and the support month by month.