This is the 4397th most frequent Japanese word.
咲い
"咲い" is not a standard Japanese word; it may be a conjugation or misspelling of "咲く," meaning "to bloom" (as in flowers).
咲いた is the past tense form of 咲く (to bloom), describing an action completed in the past.
花が咲いた。
The flowers bloomed.
咲いている is the progressive form of 咲く, used to describe an ongoing blooming process.
桜が咲いている。
The cherry blossoms are blooming.
咲くでしょう is the potential future form with an added probabilistic expression, inferring an action that may occur.