Learn Portuguese (Portugal): Ela tem um ótimo sentido de humor.

In Portuguese, most descriptive adjectives go after the noun. However, adjectives that express a personal evaluation, subjectivity, or intensity—like ótimo (great/excellent), bom (good), and mau (bad)—often go before the noun. Putting it before sentido makes the compliment feel more natural and emphatic.

Why do we use sentido here instead of senso?

In European Portuguese, sentido is used for the five physical senses, a "sense of direction" (sentido de orientação), and a "sense of humour" (sentido de humor). The word senso is mainly used when talking about judgment or reasoning, most notably in the phrase bom senso (common sense). Note that you might hear senso de humor in Brazilian Portuguese, but in Portugal, the standard is sentido.

I sometimes see the word for "great" written as óptimo. Is that the same word?

Yes, they are the exact same word! Óptimo was the standard European Portuguese spelling before the Orthographic Agreement (the spelling reform). The reform removed silent consonants, making it officially ótimo today. However, as a B2 learner reading native materials, you will still frequently encounter óptimo in older books, on signs, or from people who simply prefer the traditional spelling.