What are the other uses of the “make” command?

POSTMAP=/usr/sbin/postmap
POSTFIX=/usr/sbin/postfix

HASHES=transport access virtual canonical relocated annoying_senders
BTREES=clients_welcome

HASHES_DB=${HASHES:=.db}
BTREES_DB=${BTREES:=.db}

all: ${BTREES_DB} ${HASHES_DB} aliases.db
    echo = Done

${HASHES_DB}: %.db: %
    echo . Rebuilding $< hash...
    ${POSTMAP} $<

${BTREES_DB}: %.db: %
    echo . Rebuilding $< btree...
    ${POSTMAP} $<

aliases.db: aliases
    echo . Rebuilding aliases...
    /usr/bin/newaliases