What does a hexadecimal number, with a register in parenthesis mean in Assembly?

Question

lea 0x1c(%ebp),%eax

So, I understand vaguely what the lea instruction does, and I know those are registers, but what is this structure: 0x1c(%e

Answer 1

It is one of the many x86 addressing modes. Specifically, this is referred to as "displacement" addressing.

Since you said you used objdump and didn't specify that you used the -M flag, I'm going to assume this in the GAS syntax (as opposed to Intel syntax). This means that the first operand is the source, and the second operand is the destination.

The lea 0x1C(%ebp),%eax instruction means, "Take the value in %ebp, add 0x1C (28 in decimal), then store that value in %eax".