The usual meanings
Red roses mean romantic love. They are the classic choice for anniversaries and Valentine's Day. Pink roses suggest gratitude, admiration and gentle affection, a good fit for mothers, friends and new romance.
White roses are linked with purity, new beginnings and remembrance, so they show up at weddings and services. Yellow roses mean friendship and joy, and are a cheerful choice for a friend or a new job. Some older traditions linked yellow with jealousy, but that meaning has mostly faded.
Orange roses suggest enthusiasm and energy. Lavender roses are often linked with enchantment or love at first sight. Mixed colors can say a mix of things. If the person has a favorite color, that usually matters more than any tradition.