Some "DevOps" are "SysAdmin with a little development" while others are "Development with a little SysAdmin."
But for either you need to likely be comfortable setting up a WAMP or LAMP environment (and similar popular software, Nginx, IIS, postgresql, Cassandra, memcached, etc). along with decent familiarisation in scripting both (e.g. bash + PowerShell) and a good solid grasp in whatever languages they use (e.g. Java, Python, etc).
Overall most DevOps positions are unpaid for the qualifications they require and expect unreasonable levels of knowledge. There are people who could do DevOps but they have enough experience now so that they'd never take the salaries offered for the majority of DevOps roles (i.e. you rarely see medium-large companies after DevOps, they prefer two specialists and pay each more).
I'd definitely be careful with DevOps, unless it is a sub-10 person business they're likely just trying to cheap out on either development or systems support. In either case it speaks badly of a company.
Manage a Cloud infrastructure from creating, destroying and provisioning instances using tools like Ansible and in the past Puppet and chef.
The environments where I have worked are so large that doing things manually does not scale and you have to automate all these processes. I have to work with developers to help them setup their dev enviroments using Vagrant and have them mirror production.
Also, I have to make sure the code the developers work with is managed and deployed to our instance using automated tools like Jenkins or Travis CI. Help the developers troubleshooting networking, DNS , SSL issues once we detect bugs on production on sandbox and help them get access to logs, automate alerts using New Relic, Elastic Search .
I work with environments where I have to know and understand the whole stack. Hadoop, kafka, Django, Postgres , MySql, Mongodb and be able to pin point where our bottle neck might be when we have production problems. A lot of developers just work on one part of the system so they come to me when they need help understanding the whole stack.
My work involves helping making the developers and the business work with operations and work as a team. hence the term DevOps .
Automate all the things! that's my job
I can see a job description where many of the traits of a traditional backend developer are listed in the DevOps role, but they are not one in the same. That said, small teams will many times use a backend developer that has solid networking, hardware and automation skills to fill the DevOps role as well as his/her developer duties. We do that because we don't have the revenue yet to afford to separate those two positions.
I may be wrong