Those brackets show up when you enter a formula by hitting CONTROL+SHIFT+ENTER at the same time, instead of just enter as in
=MIN(IF(A1:A10,A1:A10))
which, when entered by hitting CONTROL+SHIFT+ENTER at the same time, will appear on the Formula Bar as
{=MIN(IF(A1:A10,A1:A10))}
The only time you enter these curly brackets yourself is when you feed some function a constant array as argument as in
=VLOOKUP(A1,{"a",1;"b",2;"c",3},2,0)
where {"a",1;"b",2;"c",3} represent a 2-column table.
Curly brackets are thus associated with the so-called array formulas and constant arrays.
Semantics... they're called braces...
See the Excel help topic for...
"Values that do not change in array formulas"