Mindfulness would be a little difficult to go into in a comment, but the one sentence answer is:

Mindfulness is spending time focused on beinf in the present, utilizing an attitude of nonjudgement and curiosity to experience reality as it is. Mindfulness practice is specific exercises focused on being mindful and creating a mindful state.

DBT is a framework for therapists that help individuals with a wide range of emotional and relational difficulties by combining principles of mindfulness with cognitive behavioral therapy principles. Lots of good videos, articles, etc. out there.

Therapist here: Mindfulness practice is truly the best bang for your buck in terms of time/effort spent to help with mood regulation.

That and learning specific distress tolerance skills taught through something like dialetical behavior therapy.