This is the configured interval, in seconds, at which the router sends EIGRP Hello packets out this interface to maintain its neighbor relationships. Because EIGRP's hold timer, which tears down the adjacency, is typically a multiple of this interval, mismatched Hello intervals between two routers on the same link are a classic and easy-to-miss cause of adjacencies that will not form or that flap. A serial WAN link commonly shows 60 seconds here versus the LAN default of 5 seconds, because slower links use longer Hello/hold timers to avoid unnecessary flaps.