Spark Streaming framework helps in developing applications that can perform analytics on streaming, real-time data - such as analyzing video or social media data, in real-time.
In fast-changing industries such as marketing, performing real-time analytics is very important. For example, advertisements can be served depending on a user's behavior at a particular time instead of the historical behavior, increasing the probability of prompting an impulse purchase.
If you want to learn Spark, I recommend this Spark Course by Intellipaat
Also, watch this video on Spark tutorial: