Translation:The lightning flashes.
-(이)네요 verb ending can be used in 2 ways:
• to express a soliloquy (~thinking to oneself aloud), an exclamation of awe, surprise.
번개가 치네요 ~ Gosh, there are lightning-strikes/bolts of lighting
• to replace the 다 ending in a neutral declarative statement.
번개가 치네요 = 번개가 치다 - The lightning strikes (flashes)