Asparagine (ASN or N) is a hydrophilic amino acid. Asparagine is cloesly related to aspartate (aspartic acid), and has the same shape. The CPK or EnzDes coloring options (found in view options can be used to tell asparagine from aspartate. Asparagine can also easily be confused with threonine.
Since the asparagine's sidechain can form hydrogen bonds with the protein's backbone, asparagine is often found near the beginning and the end of helixes, and in turns near sheets. Its role can be thought of as "capping" the hydrogen bond interactions that would otherwise be satisfied by the polypeptide backbone.
Asparagine's sidechain contains an oxygen atom which can act as a hydrogen bond acceptor, and a nitrogen atom which can act as a hydrogen bond donor. See the Sidechain Bonding Gallery and the Sidechain Bonding Table for other sidechain donors and acceptors.
For more, see Asparagine on wikipedia.