Oh Jessica dit transformation is a big topic. If you/ your school is subscribed to Gartner, a market research firm, you can check out their articles on latest IT trends (some are subscription free), or just wikipedia the terminologies new to you.

They define Digital Transformation as any enterprise-wide initativies to use latest digital technologies to improve organizational processes (trying my best to paraphrase) instead of relying on traditional methods, and by digital technologies they mean tech that relies upn the sharing and manipulation of data that is based on cloud-based architecture.

So in a nutshell, what is an intuitive way to put digital transformation? Basically you can think of it as using new technologies in businesses. These new tech includes cloud, robotics, chatbot, big data, data analytics, AI, ML and more (they are generating a lot of buzz now so you will see it everywhere on google)

HR transformation is definitely a subcategory of digital transformation. Think of it as emerging tech + HRM. For example, yout company might be using bots to screen away unqualified candidates, or they might use AI algorithms to predict a potential recruit's performance. These are just straightforward examples of tech+HRM. Remember sky is not the limit and you could literally apply any new tech into your company's business process. Precisely because of this high potentiality and wide applicability of emerging tech, companies are starting to employing new technologies and thus "digitally transform" their business processes.

Tldr: I'm no expert and you should google more :)