In Japanese, sound effects can be used to convey the sound of a particular action. The と quotation particle is used with the sound effect to quote it as a singular noun and make it a modifier to the primary verb.
Example: The rabbit continued to run like "pyon pyon".
ウサギはピョンピョンとはしりつづけた
Info
ウサギ (rabbit) is the topic of the sentence, as it is flagged with the は particle.
ピョンピョン (pyon pyon) is a sound effect used to convey the feeling of a small creature moving around. it is marked with the と quotation particle, making it a noun that modifies the primary verb of the sentence, telling us more about it.
はしり is the い-stem form of はしる (to run). This form allows the following verb to be appended to alter the meaning.
つづける (to continue) is placed into the た form, placing the sentence into the past tense. It is also attached to the prior verb はしり, together they make はしりつづけた (continued to run). The sound effect quoted earlier in the sentence tells us the way in which they ran was like “pyon pyon”.