“the word of Yahweh.” In this context, “the word of Yahweh” refers to direct revelation.
“visions were not frequent.” This refers to revelation, which was often given as a vision, but as we see in the context, audible revelation from God was also recognized, even by Eli, who likely had not gotten any in a while (1 Sam. 3:4, 6, 8). At this time in Israel’s history, due to the sin in the priesthood and among the people, revelation from God was rare and thus not frequent. However, there were still some prophets around (cp. 1 Sam. 2:27). We should also note that the Hebrew can be “not widespread” as well as “not frequent,” and both meanings are likely correct.
We should notice however that the reason that revelation was rare was due to the sin and disobedience of the people. God always wants to speak to His people and guide and bless them, yet sin separates people from God: “your iniquities have made a separation between you and your God, and your sins have hidden his face from you, so that he does not listen” (Isa. 59:2). Loving God involves working diligently to obey Him, and that will yield the wonderful benefit of being in greater communication with God.