Felwood is a level 48-55 zone. Passage from Felwood to Winterspring or Moonglade is obtained by walking through a tunnel that goes to each of these zones. Unless you have unfriendly or higher reputation, the Furbolgs will attack you!
Primary interest in the Timbermaw Hold faction is in the vendor items, and in gaining passage through Timbermaw Hold to make initial visits to Winterspring and Moonglade.
Timbermaw Hold reputation begins at Hostile (2500/3000), which means that 500 points of positive reputation (Unfriendly status) is needed before Timbermaw Hold Furbolgs will no longer attack on sight (blocking passage to Winterspring and Moonglade). Luckily, Timbermaw Hold faction quests can be received from Grazle even while Timbermaw reputation is hostile.
Warning: it is ill-advised to fight Timbermaw Furbolgs. Each kill loses 25 faction points, which will only extend your long grind to gain reputation later. It is well worth the effort to gain the initial 500 reputation points needed for "Unfriendly" status, rather than fight your way through Timbermaw Hold to Winterspring or Moonglade.
Upon different reputation status, i.e. honored, revered, exaulted, you can purchase specific profession recipes, which are pretty good.
Also, one thing most people do not know, is that timbermaw rep CAN be raided! So grab as many people as you can, and kill, kill, kill those furbolgs!