If he has not already received a bible and catechism from his Church those are the first choices
Catholic youth Bible from Saint Mary’s Press is a good choice, either NAB or NRSV translation, about $28 more for hardcover.
Catholic Catechism for Adults from the USCCB website, $25 is a great catechism that will be useful all through life
Daily Roman Missal (about $40-50) or a subscription to Magnificat Magazine ($39/year) until the new revisions of the missal are available is what I tell parents for a first choice.
Shorter Christian Prayer $15-18 depending on binding, good start on the Liturgy of the Hours