Protection is not a single ability but a family of static abilities. A permanent or player will not have Protection; it will have Protection from <quality>. For example, it might have Protection from artifacts, Protection from white/blue/black/red/green, Protection from creatures, etc. If a permanent or player has protection from multiple different qualities, all of them apply. Protection has a number of effects.
- Any kind of damage that would be dealt by cards with the quality to the permanent/player with protection is prevented.
- A permanent or player with protection may not be targeted by spells, or by abilities from cards with the given quality (including spells and abilities played by the controller of the permanent itself).
- Auras and Equipment with the given quality cannot be attached to the object, and, if they are already attached, are sent to the graveyard (Auras) or become unattached and remain on the battlefield (Equipment).
- If a creature has protection, it may not be blocked by other creatures with the quality. This is an evasion ability. If both attacker and defender creatures have protection from each other, the defender still cannot block the attacker.
An easy way to remember what protection stops is to remember the acronym DEBT: Damage, Enchant/Equip, Block, Target. Protection does not affect anything that does not do one of those four things. A permanent/player with protection may still be affected by effects or abilities that do not specifically "target" it. For example, Progenitus is a 10/10 creature that has protection from everything.
Sudden Spoiling is an instant that reads: Creatures target player controls become 0/2 and lose all abilities until end of turn. Because Sudden Spoiling targets a player Progenitus is not being targeted. When the instant resolves, Progenitus becomes 0/2 and loses its protection ability for the turn. Likewise if a player where to to play Wrath of God, which destroys all creatures, but does not target Progenitus specifically, it would still be destroyed.
So looking at your questions:
Will a creature with "Protection from blue" be unaffected by Propaganda?
Will a creature with "Protection from lands" be unaffected by the Tabernacle at Pendrell Vale?
Propaganda
2U
Converted Mana Cost:3
Types: Enchantment
Oracle Text: Creatures can't attack you unless their controller pays 2 for each creature he or she controls that's attacking you.
The Tabernacle at Pendrell Vale
Converted Mana Cost: 0
Types:Legendary Land
Oracle Text: All creatures have "At the beginning of your upkeep, destroy this creature unless you pay 1."
Propaganda and / or The Tabernacle at Pendrell vale, nor the ability it grants to creatures contains the word: "target", therefore protection doesn't apply.
