Hi Ann,
In-Closeness centrality measures the degree to which a node can be easily reached *from* other nodes (i.e. using edges coming in towards the node) where easily means shortest distance.
Out-Closeness centrality measures the degree to which a node can easily reach other nodes (i.e. using edges out from the node), and easily again means shortest distance.
Closeness is traditionally run on a connected, undirected graph in which case in-centrality = out-centrality for each node and the measure is called Closeness Centrailty.