The 516096 bits of embedded block RAM support a small frame buffer or FIFO.
I/O and package — what fits on the board
The package is 144-EQFP (20x20 mm) with 81 I/O on the outer rows. Surface mount only — no socket option for field swapping. If this is a field-replaceable card, plan for a board-level swap rather than a chip-level one.
How it sits against the Cyclone IV GX sibling
The closest functional peer in the Cyclone IV family is the EP4CGX15BF14C8N (GX series). Both share a similar logic density (14400 LEs in the GX vs 15408 in the E) and nearly the same block RAM (552960 vs 516096 bits). The deciding difference is that the GX variant includes transceivers for serial protocols (PCIe, Gigabit Ethernet) while the E series is a pure logic-and-I/O device. If your design does not need high-speed serial lanes, the E part saves cost and keeps the pin count lower (81 I/O vs 72 I/O in the GX).