The fillet .04 is for the Ø.378 hole edge.
+.001/-.001 tolerance is for the Ø.378 hole (since is symmetrical it is usually written as ±.001)
↓ (the down arrow with line on top) is the symbol for depth and define depth for the Ø.378 hole.
Please refer GD&T reference books ..
These are some very basic dimension symbols and methods.
You really need to understand basic geometric dimensions and drafting methods before you are going to do designing.
You should be able to easily find some good sources for this information.
You can look for GD&T (Geometric Dimension and Tolerance) references as Richie More said or look for a machinist handbook.
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