According to the United States Constitution, the Supreme Court is filled by nominations directly from the president of the United States. The President is responsible for nominating judges to the Supreme Court, and the Senate is responsible for confirming those nominees. In general, the Senate has been very loose with confirming nominees, with very few of them facing a tremendous amount of scrutiny; however, during the past few presidential cycles, this process has gotten a bit tenser. For example, the Senate refused one of Obama’s appointees to the Supreme Court, instead of deciding to wait until the next presidential election. When the president nominates someone to the Supreme Court, and when that person is confirmed, they have that seat for life.
The president who nominated the most Supreme Court Justices was George Washington. During his time as president, he had to fill the very first supreme court. Then, he had to fill other seats as those justices continued to retire. Some members of the Supreme Court decide to serve until they die. Because life spans were much shorter back then, he had to nominate more members to the council. Of note, there is no set number of justices on the Supreme Court, and it can be changed over time. During the course of his presidency, George Washington nominated 11 Supreme Court Justices.
Aside from George Washington, Franklin Delano Roosevelt nominated the most justices. During the course of his presidency, he nominated nine justices to the Supreme Court. He is also the only president to serve more than two terms, so he was in office longer and had more opportunities to do so.
Even though Donald Trump was only in office for one term, he did have an opportunity to nominate three Supreme Court Justices. First, the Senate stonewalled the appointment of Barack Obama, so Donald Trump had to nominate someone to the Supreme Court as soon as he took office. Then, during the course of his career, he nominated two more justices to the Supreme Court. His justices include Neil Gorsuch, Amy Coney Barrett, and Brett Kavanaugh. His nominations have been controversial, but they were eventually confirmed by the Senate. They will be on the bench until they decide to retire or until they pass away.
So far, Joe Biden has had one Supreme Court nomination. He nominated the very first African American female to the Supreme Court, and she was eventually confirmed by the Senate. It is unclear exactly how many nominations he will have during the course of his presidency. Right now, the chief justice is John Roberts, and he does not show any signs of retiring. He has struggled to control the other justices on the bench so far, and it is unclear whether he will retire. Unless someone else retires or passes away, he will not nominate anyone else to the Supreme Court.