It's a plan to accomplish something with digital tools (like social media, search engine optimization, and eCommerce). Basically, digital strategy makes design so useful that it does work for you, even while you are sleeping or eating dinner with your family.
1. Everything you post on your company's website and social media should work toward your goals. Everything. (Not just random pictures of kittens.) Before you post something, ask yourself, "What is the point of this, and how will it help me reach my short-term goal?" Long term?" If you can justify it, post away. Post your heart out.
2. Think about your current customers' needs. Are you meeting them? Can you use digital tools to meet their needs in a better/more efficient/more authentic way?
3. Are you working with your dream customers? Are you currently reaching them, or do they not know about your company? Where can you find your dream customers?
4. Do the words on your website appeal to your dream customers? Do they sound too technical and boring? Do they genuinely sound like something you and your employees would say? How can you explain your services and products in a way that your ideal customers will understand?
Those are the basic elements of digital strategy-- defining goals and using technology to constantly move toward those goals.