他們第一箇孩子出生了，很高興。

They were pleased at the birth of their first child.

Source: Tatoeba

Sentence Composition

1 他們 tāmen they; them
=2 第一 dìyī
  1. first
  2. most important; primary; foremost
=2 第一 dì-yī
  1. (literally, figuratively) first; 1st
  2. being the most important consideration; being essential, or a priority; coming first
  3. first; 1st
  4. firstly
  5. number one; #1; first (in a test, competition, etc.)
3 箇 gè variant of 个 gè
4 孩子 háizi child
5 出生 chūshēng to be born
=6 了 le
  1. (completed action marker)
  2. (modal particle indicating change of state, situation now)
  3. (modal particle intensifying preceding clause)
=6 了 liǎo
  1. to finish
  2. (used with 得 dé or 不 bù after a verb to express (im)possibility, as in 忘不了 wàngbuliǎo "cannot forget")
  3. (literary) (usually followed by a negative such as 无 wú or 不 bù) completely (not); entirely (not); (not) in the least
  4. to understand clearly (variant of 了 liǎo)
=6 了 liǎo
  1. (of eyes) bright
  2. clear-sighted
  3. to understand clearly
=6 了 liào unofficial variant of 瞭 liào
7 很 hěn
  1. very; quite
  2. (also, often used before an adjective without intensifying its meaning, i.e. as a meaningless syntactic element)
8 高興 gāoxìng
  1. happy
  2. glad
  3. willing (to do sth)
  4. in a cheerful mood