There is a big difference depending on where your software is going to run. You would not write the same code for an embedded device with extreme constraints, than for a big enterprise server which will be usually underutilized. The same goes for the cloud: you do not write the same code if you are accessing a file locally, than if you are accessing an object on Amazon S3 or Azure Blob. They behave in a different way and, if you do not account for that (e.g. latency) your code will be subpar to say the least.
Without having more information about the job description, it is difficult to assume what they mean. I will just give you some tips about what would be generally expected. For a junior or middle position, it may be just familiarity with how to use the services (e.g. using the relevant SDKs), and what they are actually are. There may be frequent conversations with people mentioning EC2, or S3, or RDS, and they want the new team member to be able to follow them. And you may be tasked with stories such as "Store the results of X in an S3 bucket".
For a more senior position, it could also involve being able to design solutions based on the cloud. Knowing how to leverage the services to solve the particular problem that your applications needs to solve, properly designing a high availability system, maybe lead a migration from on-premises to the cloud, etc. The more senior you are, the more time you will spend on this type of tasks.
Then again, it may also require that you are able to implement those solutions yourself. Meaning getting into the actual CLI/Console and create an instance, or a database, or debugging a network issue. This would be mostly for a system administrator role (or a "cloud engineer"), and most companies will have specific people for this, but still, in some teams or companies they may expect this from developers.
And of course, it could be just a bogus requirement, with someone (probably non-technical) just copying information over from other offers without understanding what they are demanding. This is also probably a warning sign for the job, but still, it happens.