I will answer the last question first. No, it doesn’t mean if you are not a Catholic you will not be saved. Christ died for everyone so everyone has a chance to be saved, Catholic or not.
So what does that phrase in your first question mean? It simply means that the Catholic Church (and her alone) claims to have the complete set of sacraments to assist in salvation. Catholics view these sacraments as“tools" for salvation; achieving salvation is easier with these tools than without.
This doesn’t mean Catholics look down on other religions, no. Gaudium Et Spes, from Vatican II, expresses the pastoral teaching on Catholicism with relation to society and other religions. It teaches that the Catholic Church respects all religions because they show certain truths about God.