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"Si" is a form of "si", a conjunction which is often translated as "if". "Mejor" is an adjective which is often translated as "better". Learn more about the difference between "si" and "mejor" below.
si()
A conjunction is a word that connects words, phrases, clauses, or sentences (e.g., The cat and the dog slept.).
A masculine noun is used with masculine articles and adjectives (e.g., el hombre guapo, el sol amarillo).
mejor()
An adjective is a word that describes a noun (e.g., the big dog).
a. better (comparative)
Tu bici nueva es mejor para la montaña que tu bici anterior.Your new bike is better for the mountains than your old bike.
2. (recovered)
An adverb is a word that describes a verb, an adjective, or other adverbs (e.g., to run quickly, very tired).
a. better (comparative)
Me siento mejor que ayer.I feel better than yesterday.
Ella canta mejor que tú.She sings better than you.
4. (preferably)
a. no direct translation
The following examples show ways to translate this word or phrase without using a direct equivalent.
Mejor decírselo, yo creo.I think it would be better to tell them.
Mejor vamos otro día.We'd better go another day.
