Without the right tools, creating a piece of art can be difficult - this is especially true for painting. Having high quality paint is one thing, but that only takes you so far if you don't have high quality paint brushes.
For starters, there are some standard paint brushes typically used when painting with acrylic paints:
The Filbert brush is a great place to start.
Think of this as your general, all-around (no pun intended) brush that's something of a cross between a Round brush and a Flat Brush. Filberts can be used for details if need be and it can cover space or be used for blending.
After that, the Round brush starts getting more specific.
Round brushes can handle filling in small areas, outlining, some details. This is a solid paint brushes, and there are plenty of others to take on different types of painting.
Next, there's Pointed Round.
As the name implies, very similar to the Round tip, but narrower for finer details, spotting and line work.
Those two were general detail work, but the Flat brush is for taking on more space.
Flat brushes are great for filling in wide spaces and shading. When you need a larger area covered, flat brushes are your best bet for those bold strokes.
An Angular Flat brush has a similar shape to a Flat of course, but the Angular aspect changes up its function.
Much like a Flat brush, this one can cover larger spaces if need be. The angular tip is made for curved strokes and filling in corners.
Finally, there's the Detail brush.
As one would assume, Detail brushes are made for very fine, minute details. Imagine painting a portrait the size of a quarter underneath pull tab on the back a sneaker. It's very doable, and a detail brush is the way to pull that off.