The phrase "that's pertinent" refers to something that is relevant or important to the topic being discussed. Some synonyms for this phrase include "that's applicable," "that's germane," "that's related," "that's significant," "that's material," and "that's appropriate." Each of these synonyms highlights the importance and relevance of the information being discussed and helps to convey the idea that the topic is both interesting and meaningful. Whether you are discussing a complex issue or just trying to make small talk, using these synonyms can help to make your conversation more engaging and informative.