Content Strategy is a very broad term. Content strategy is the approach and method of creating, managing, and delivering content to its intended audiences, which can make it a bit problematic in that it encompasses so many things and applies to many industries.
One use of the term that has become very prevalent in recent years is its use in marketing, where it could be read as shorthand for “content marketing strategy”. In that sense it relates to planning a strategy for how to produce content such as blog articles, webinars, podcasts, social media posts, and more, from a marketing perspective.
However, from a technical communication perspective the term content strategy takes on a different meaning. It involves complex tasks such as conducting content inventories and audits, developing taxonomies, creating content models, and organizing content effectively to support documentation planning and information architecture.
An example of a primer on this meaning of the term content strategy would be Managing Enterprise Content – A Unified Content Strategy.